I ask you to solve a few Olympiad problems. 5th grade 10

First, spiders have 8 legs, dragonflies have 6 legs and 2 pairs of wings, and cicadas have 6 legs and 1 pair of wings.

There are 13 pairs of wings, and the wings of the cicada are singular, so there are only 6 cases of 13 = 1 + 12 = 3 + 10 = 5 + 8 = 7 + 6 = 9 + 4 = 11 + 2.

In each case, count out the number of legs, and then 128-legg, if divisible by eight, then the quotient is the number of spiders.

According to the above method, 1, 12 cicadas, 6 dragonflies, the number of legs = 42 then 128-42 = 86 is not divisible by eight, so it is rounded.

The final result is 10 spiders, 5 dragonflies, and 3 cicadas.

First of all, the number of girls is 60 - the number of boys, and the total number of boys planting trees is 5 * the number of boys.

Because there are 100 more boys than girls.

So the total number of trees planted by girls is 5 * the number of boys - 100

Because the total number of trees planted by girls is 3* (60 - the number of boys).

So 5 * number of boys - 100 = 3 * (60 - number of boys), so the number of boys is 35.

So we know that the total number of trees planted by boys is 175 and that of girls is 75.

A will do it alone for 4 days, and B will do it alone for 6 days.

In fact, after A and B did it together for 4 days, B did it alone for 2 days.

Then A and B can produce 4 * 60 = 240 parts in four days.

So B did it alone for 2 days and produced 310-240=70 products.

So B produces 35 per day.

So A produces 60-35=25 per day.

If you're satisfied, add me.

1.There are 10 spiders, 5 dragonflies, and 3 cicadas.

2.275 for boys and 175 for girls.

1. One less condition should be more solutions. I can't use equations, so I have to solve them exhaustively.

(1) A basket of apples is 40 catties, and a basket of pears is 50 catties.

2) 37 roots.

3) The road is 3600 meters long.

4) Flower cloth yuan, white cloth yuan.

5) There were 24 kilograms of oil in the bucket.

Solution: Use the nine numbers from 1 to 9 once to form three three-digit numbers, and the sum of these three numbers is the largest, then the hundred digits must be 7, 8, and 9

4,5,,6 in the tenth place and 1,2,3 in the single place

is divisible by 7, 742,756,763,854,964,861,812 is divisible by 9

Characteristics of numbers divisible by 9: The sum of the digits is divisible by 9.

7,5,6；8，4,6；9，3,6；9,4,5 divisible by 11:

The difference between the sum of the numbers on the odd digits and the sum of the digits on the even digits is a multiple of 11.

825 or 924

Use 1 to 9 once each, and if the sum of the numbers is as high as possible, it is best to start each of the 3 numbers with 789.

The maximum values are taken as 935(11)864(9)721(7) and 2520

To make the sum of these three numbers as large as possible, the three numbers should be placed in the hundred place, and the three numbers should be placed in the ten place as much as possible. The answer is as follows: Three three-digit numbers that are divisible are

Group 1: Group 2: Group 3:

Supplementing the common multiple of the request.