1 2 3 4 5 6 7 8 9 10

3 10 32 (6,4) 1/ 10 15 0.3 3 1 18 80 3

Second, the calculation problem.

1 1、 1.25× 17.6+36. 1÷0.8+2.63× 12.5

= 1.25× 17.6+36. 1× 1.25+26.3× 1.25

= 1.25×( 17.6+36. 1+26.3)

= 1.25×80

= 100

12, a food store: 50 ÷ 8 = 6...2

50-6=44 (box)

Just buy 44 boxes and get 6 free.

4×44= 176 (yuan)

B food store:

4×50=200 (yuan)

200×90%= 180 (yuan)

C food store:

200> 100, so buy a 15% discount.

200×85%= 170 (yuan)

170< 176< 180

Answer: A food store needs 176 yuan, B food store needs 180 yuan, C food store needs 170 yuan and C food store needs 170 yuan.

The cheapest one.

13, Solution: Assume that all the purchased air tickets are economy class air tickets and business class air tickets are:

( 13080-720× 16)÷( 1500-720),

= 1560÷780,

=2 (sheets),

Then the economy class ticket is:

16-2= 14 (sheets);

A: The ticket for Wang Mai Junior is 14 economy class.

14. The time for the son to arrive at point A is: (400÷ 100)× 19=76 seconds.

Father: (200+70)÷ 100×20=54 seconds;

On the anticlockwise road from A to B, my son has to run for 76÷2=38 seconds.

Father can run for 200÷ 100×20=40 seconds.

40-38=2 seconds.

According to the trial calculation, 76× 5 ÷ 54 = 7...2.

That is, when the father and son met for the first time, the son had finished the seventh lap, that is, he was running the eighth lap.

So the son met his father for the first time when he ran the eighth lap.