There are 18 spiders, dragonflies, and cicadas, with a total of 118 legs, and 20 pairs of wings.

Because spiders don't have wings, and dragonflies and cicadas have the same total number of legs, the wings are left behind.

Set the question to. There are 18 spiders and dragonflies, and 118 legs. And spiders have 8 legs, dragonflies have 6 legs, how many are there in each of the two animals?

It just makes it simpler.

Let's assume it's all spiders.

Then there are 8*18=144 legs, which is more than 144-118=26 legs.

However, each spider has 8-6 = 2 more legs than a dragonfly.

So there are 26 dragonflies 2=13.

There are 18-13=5 spiders.

Because of the previous adaptation of the title, the dragonfly and the cicada were combined.

So those 13 should be the total number of dragonflies and cicadas.

Then we will face the second problem:

Dragonfly 2 pairs of wings, cicada 1 pair of wings, 13 of the two animals, 20 pairs of wings, how many of them are there?

And then we're going to do the same thing.

Assuming it's all cicadas, then there should be 1*13=13 pairs of wings.

20-13 = 7 pairs less than it actually is.

Each cicada has 2-1=1 pair of wings less than a dragonfly.

So there are 7 1 = 7 dragonflies.

There are 13-7 = 6 cicadas.

Finally, to sum up.

A: There are 5 spiders, 6 cicadas, and 7 dragonflies.

It can be solved with a system of ternary equations. Spiders, dragonflies, and cicadas are x, y, and z. Then list the equations:

x+y+z=18

8x+6y+6z=118

2y+z=20

Then solve this system of equations to get x=5, y=7, z=6

There are 5 spiders, 6 cicadas, and 7 dragonflies.

22 3-20 3 = 6 (only) 22 pairs of wings 3 types of insects - 20 insects 3 types of insects = insects without wings (spiders) 20-6 = 14 (only) 20 insects - number of spiders = number of dragonflies + cicadas.

14 2-22 = 6 (only) 14 insects (cicadas + dragonflies) 2 pairs of wings - 22 pairs of wings = one pair of wings of insects (cicadas).

20-6-6 = 8 (only) 20 insects - number of cicadas - number of spiders = number of dragonflies.

A: 6 spiders, 6 cicadas, and 8 dragonflies.

Think of dragonflies and cicadas as a 6-legged animal.

Assuming that all are 6 legs, 6 18 = 108 bars.

Spiders are: (118-108) (8-6) = 5.

Dragonflies and cicadas have a total of 18-5=13 dragonflies.

Suppose all dragonflies have wings: 13 2 = 26 pairs.

Then the cicadas are: (26-20) (2-1) = 6.

Dragonflies are: 13-6=7.

Assuming that all of them are cicadas, then there are 18 6 108 spiders and 2 5 spiders

Dragonflies and cicadas have: 18 5 13 (only).

If all the remaining cicadas are cicadas, the wings are: 13 1 13 (pairs) Extra: 20 13 7 (pairs) The extra wings are dragonflies, and the number of dragonflies is 7.

6 cicadas, 7 dragonflies, 5 spiders.

First divide the 8 and 6 into 2 categories, let them all be 8, 18 8 144,144 minus 118 26,26 (8-6) = 13, 18-13 = 5,

If you use ternary equations, isn't it a little bit difficult for a sixth-grader?

"There are 20 spiders, dragonflies, and cicadas. There are 130 legs in total, and the wings are paired. Among them, the spider has 8 legs; Dragonfly 6 legs, 2 pairs of wings".

How many of the three animals are there? This is a wrong question, the conditions are contradictory, and there is no solution to this problem. Because.

Cicadas and dragonflies are both insects with 6 legs and 2 pairs of wings. There are 22 pairs of wings, 22 2 = 11 (only) - 11 cicadas and dragonflies in total; 20 11 = 9 (only) – there are 9 spiders. However, 6 11 = 66 (strips) – 11 insects (cicadas and dragonflies) have a total of 66 legs;

8 9 = 72 (strips) – 9 spiders have a total of 72 legs;

Even if the number of legs is not contradictory, it is impossible to find out how many cicadas and dragonflies there are, because there is no information to distinguish between them. Doesn't the questioner have any knowledge of biology?

Nearly 1 million species of insects have been discovered, all with six legs! Wingless insects include the wingless subclass Stoneworm C (a combination of "worm" and "C") and Tasseltail (about 700 species in total); There are also springtails, protoceras, and diploceda, which have a total of about 3,000 species, and some biologists classify them into the class of insects, and some biologists classify them into another class - hexapods; The wings of lice (about 3,150 species), fleas (about 1,800 species), female soft-shelled turtles and aphids, and worker ants of the order Hymenoptera have degenerated. The hind wings of diptera mosquitoes and flies have become balance rods.

Except for a few of the above species, all other insects have four wings.

Dragonflies, belonging to the order of insects dragonflies, are divided into dragonflies, dragonflies, etc., and "dragonflies" are their collective names; Dragonflies have six legs and four wings!

Cicadas, belonging to the insect class Hemiptera (some biologists classify it as the order Homoptera) cicada family, there are about two or three thousand species. Cicadas also have six-legged four-winged, but the front wings of the cicada are large and the hind wings are small, and the front wings usually cover the hind wings, and they only fly when they fly. If anyone can find a cicada that isn't six-legged and four-winged, then congratulations on discovering a new species and you'll get the naming rights!

But before you name it, you need to learn the basics about insects!

5 spiders, 7 dragonflies, 8 Chan.

Dragonflies and cicadas are both 6 legs, let's say 18 animals.

Since they all have six legs, 6*18=108, but there are 118 legs, 10 more, indicating that there are 10 (8-6)=5 spiders.

The title changes to 13 dragonflies and cicadas, and if there are 20 pairs of wings, assuming that they are all cicadas, then there are 13 pairs of wings 20-13=7, and if there are 7 dragonflies and 1=7, there are 6 cicadas.

Assuming that each animal has 6 legs, then 18 animals have a total of 18*6=108 legs, and now there are 118 legs, and there are 10 more legs, which must be.

If there are 5 more spiders, the answer should be 5, so there are 13 dragonflies and cicadas; In the same way, if the dragonfly and the cicada are both a pair of wings, there should be 13 pairs of wings, and there are 20 pairs of wings, and there are 7 more pairs, so the dragonfly should be 7, then the cicada is 6.

Think of dragonflies and cicadas as a 6-legged animal.

The assumption is all. 6 feet, 6 18 = 108 strips.

Spiders are: (118-108) (8-6) = 5 dragonflies and cicadas in total: 18-5 = 13.

Suppose all dragonflies have wings: 13 2 = 26 pairs.

Then the cicadas have: (26-20) (2-1) = 6 dragonflies have: 13-6 = 7.

With a white order, all insects are.

Du put away 6 legs, and the dragonfly and the cicada both crawled on the ground, and only the spider stood on two feet.

118-18*6=10 10 2=5 There are 5 spiders standing on their feet. There are 13 dragonflies and cicadas.

At the sound of an order, the winged ones folded a pair, the cicada turned into a round light, and the dragonfly still held a pair of wings.

、、、 not the original book

Think of dragonflies and cicadas as one because both have 6 legs.

Let's say it's all spiders:

With legs: 8 18 = 144 strips.

More rounds: 144-118 = 26 pieces.

Dragonflies and cicadas total: 26 (8-6) = 13.

Spider Answer: 18-13 = 5 pcs.

Again from the wing analysis:

Let's say it's all dragonflies.

Winged: 13 2 = 26 pairs.

More: 26-20 = 6 pairs.

Then the cicadas are: 6 (2-1)=6.

Dragonflies are: 13-6=7.

A: 5 spiders, 7 dragonflies, and 6 cicadas.

Chop the legs.

Every small movement bai

The object is cut off first. du6 legs, cut off in total:

18 zhi6 = 108 pcs.

There are 118-108 = 10 daos left.

At this time, neither the dragonfly nor the cicada answered their legs, only 8-6=2 legs remained for each spider, and the spiders had 10 2=5 spiders.

There are 18-5=13 dragonflies and cicadas in total.

Reuse the wings to do it.

Each critter pulled off 1 pair of wings, and there was left:

20-13 1 = 7 pairs.

At this point, the cicadas have no wings, and each dragonfly has 2-1=1 left with 7 1=7 pairs of dragonflies.

There are 13-7 = 6 cicadas.

22 copy 3-20 3 = 6 (only) 22 pairs of wings 3 species of insects attack - 20 kun.

Bai insect 3 kinds of insects = insects without wings (spiders) du20-6 = 14 (only) zhi

20 insects - number of spiders dao = number of dragonflies + cicadas 14 2-22 = 6 (only).

14 insects (cicadas + dragonflies) 2 pairs of wings - 22 pairs of wings = insects (cicadas) with one pair of wings 20-6-6 = 8 (only).

20 insects - number of cicadas - number of spiders = number of dragonflies Answer: 6 spiders, 6 cicadas, 8 dragonflies.