Use your brain to solve a math problem in the second grade of elementary school, ask your friends to

Let's say: brother now x sister y then: x-y=y-6 21-x=x-y solution: y=11 x=16

i.e. elder brother 16 sister 11

Suppose my sister is now x years old and my brother is now y years old.

The difference between the two is (x-6) years, that is, (y-x) years.

x-6=y-x

y+（x-6）=21

The solution is y=16

x=11

Suppose my sister is now x years old and my brother is y years old, {x-6=y-xy-x=21-y

x=11 y=16Wow

21-6) 3=5 is the age difference between older siblings.

My sister is now 5+6=11 years old.

My brother is now 11 + 5 = 16 years old.

Or so: let's say: brother now x sister y then: x-y=y-6 21-x=x-y solution: y=11 x=16

My brother is 16 years old, my sister is 11 years old, I can do the math, but I don't know what to say about the second grade

My brother is 16 years old and my sister is 11 years old.

I guess that's how it should be.

21-6) 3=5 is the age difference between older siblings.

My sister is now 5+6=11 years old.

My brother is now 11 + 5 = 16 years old.

Let's say: brother now x sister y then: x-y=y-6 21-x=x-y solution: y=11 x=16

My brother is sixteen years old and my sister is eleven years old.

I read 8 pages a day, and I read them in 12 days.

So, a fairy tale book has a total of 8 * 12 = 96 pages.

Xiaoxiao reads 4 pages a day.

So, it takes 96 4 = 24 days.

1. The three teams repaired a total of 52 chairs, the first group repaired 20 chairs, and the second group repaired 18 chairs. How many repairs did the third group have?

2. A pair of slippers is 8 yuan, and a pair of socks is 4 yuan. Xiao Ming took 20 yuan to buy a pair of slippers and a pair of socks, how much yuan should he get back?

3. There are 96 storybooks in the library, 28 of which were borrowed in the first week and 30 in the second week

4. There were 35 dragonflies and butterflies in the flowers, 6 flew away and 12 flew in. How many dragonflies and butterflies are there in the flowers now?

5. There are 35 trucks and 24 cars in the parking lot. 17 drove away, how many are there now?

6. Xiao Ming made 18 green flags and 32 red flags. Give 14 noodles to the kindergarten, how many noodles does Xiao Ming have now?

7. The baker made 54 loaves of bread, Xiao Ming bought 19, and Xiao Hong bought 25. How many more can you buy?

8. The three teams caught a total of 42 bugs, the first team caught 18, and the second team caught 16. How many bugs did the third team catch?

9. There were 46 passengers on the bus, 19 people got off the train after arriving at the station, and 15 people came up. How many people are in the car now?

10. There are 51 people in Class 2 (2), 25 people skipping rope, and 8 people shooting balls. The rest kick the ball, how many people kick the ball?

11. There are 73 trees, 26 apple trees, and 38 apricot trees in the orchard. The rest are peach trees, how many peach trees are there?

12. There are 45 people doing exercises, of which there are 3 rows of girls, 6 people in each row. How many boys are there?

The sum of the middle two numbers = 2100*2 - (100 + 200 + 300 + ..)800) so fill in 200, 400 in the middle

Fill in the top three

Fill in the following three

I didn't learn equations in elementary school.

I'll tell you.

He tied the rope into two strands.

You can think of it this way.

He tied the rope into a single strand, and there was an extra 9 meters of rope outside the wellhead.

Now throw the other end into the well.

It becomes a double strand.

Now 1 meter more.

So the length is.

9-1=8m

However, there are many wellheads.

1m so.

The depth of the well is 8-1 = 7 meters.

So the rope is long.

8 2 = 16 meters.

Xiao Ming asked Xiaobai for 100-25=75 yuan.

Another loss of a bottle of water = 18 dollars.

75 + 18 = 93 dollars.

Xiao Ming ended up losing 93 yuan.

Xiao Ming found Xiao Bai:

100-25=75 (yuan).

Another bottle of water was lost, and a bottle of water was 18 yuan.

Total loss: 75 + 18 = 93 (yuan).

Answer: Xiao Ming lost 93 yuan in the end.

1. Xiaobai got water and 75 yuan, a total of 93 yuan;

2, Xiao Ming also Xiao Huang 100;

3. Add up to get 193 yuan.

This question does not look at the process, but only at the initial state and the final result:

Xiao Ming's original asset was a bottle of water, worth 18 yuan.

In the end, Xiao Ming had no assets and found Xiaobai 75 yuan in change, and lost 100 yuan to Xiaohuang, which is equivalent to minus 175 yuan.

Losing money 18 + 175 = 193 yuan.

Solution: Xiao Ming lost a total of 75 bottles of mineral water and the change he gave to others, so he should have lost 18 + 75 = 93 yuan.

193 yuan, gave Xiaohuang 100 really, lost 100, and gave Xiaobai 75 yuan real money, and the cost of 18 yuan of mineral water.

But if the questioner's meaning contains a bottle of mineral water, the profit is also considered a loss, it is 200 yuan.

In fact, the purchase price of spring water is 18 yuan, plus 75 yuan for Xiaobai, the actual loss: 18 + 75 93 yuan.

100-(25--18)=93

Pay attention to the angle of considering the problem, earn 7 yuan, and receive a 100 yuan counterfeit currency, so you lose 93 yuan. In fact, the process is negligible.

830 11 = 830 11 minutes minutes.

A: It takes about minutes.