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Primary school mathematics consultation
1.

According to "1 bag of rice is equal to the weight of 2 bags of flour", we can try to change the weight of 50 bags of flour into the weight of rice (50÷2 = 25, and the weight of 50 bags of flour is equivalent to the weight of 25 bags of rice), so this question only leaves the amount of 1 bag of rice, 1 bag of rice.

2250(20+50÷2)= 50 (kg)

You can also change the weight of 20 bags of rice into the weight of flour, and find the weight of 1 bag of flour, and then find the weight of 1 bag of rice. It can be calculated as follows:

2250(20×2+50)= 25 (kg) 25×2 = 50 (kg)

2.

Solution: Let the price of each pen be X.

Because 12÷2=6 18÷3=6.

So 12 pen is as expensive as 18 ballpoint pen.

57.6÷2=28.8 (yuan)

12X=28.8 X solution: 2.4 (yuan)

And because the price of two pens is as much as that of three ballpoint pens, 2.4×2=4.8 4.8÷3= 1.6 yuan.

A: 2.4 yuan for each pen, ballpoint pen 1.6 yuan.

3.

Solution: make bananas x yuan.

5x=4(0.4+x)

5x= 1.6+4x

x= 1.6

A: Bananas per kilogram 1.6 yuan.

4.

There are x chickens. 2x+4(29-x)=92

x= 12

Only 29- 12= 17

12 chicken and 17 rabbit.

5.

Set the number x to 5 points,

Then 5x+4(2 1-x)= 100.

x= 16

6.

Suppose it's all 2 cents.

36*2=72 (point) 99-72=27 (point)

5-cent coin: 27/(5-2) = 9 (pieces)

2-cent coin: 36-9=27 (pieces)

7.

Let's assume that 20 stamps are 4 cents each, which will be worth 80 cents.

There is a difference of 20 points between 1 yuan, so if you change a 4-cent stamp into an 8-cent stamp.

It will make up the difference of 20 points to 4 points, so you need to change 5 4-point stamps into 8-point stamps.

So there are five 8-cent stamps and 15 4-cent stamps.

Or set up an X ticket that can buy 4 points. You can buy 8-cent porn. X+Y=20.4X+8Y= 100, and X= 15 can be obtained. Y=5。

8.

The answer is: 5/9

Suppose you bought X tickets for A and 50 tickets for B.

Equation 0.5*x+0.35*(50-x)= 19.6.

The solution is x= 14.

That is, A has 14 votes, and B has 50- 14 votes = 36 votes.

The money spent on buying tickets = 0.5 *14 = 7; B =0.35*36= 12.6.

7/ 12.6=5/9 is the ratio of money A to money B.