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Math application problems in the first day of junior high school
1. Each class has to compete with other classes12-1=11. If this profession wins X games, it loses (1 1-x).

2x+( 1 1-x)= 18。

solve

x=7

1 1-x=4

So this class won seven games and lost four.

2( 1), original price eggs per 14/30 yuan.

After buying two boxes of special eggs, Li Ming actually consumed 30*2-20=40 eggs. According to this calculation, each egg uses12 * 2/40 = 3/5 =18/30 yuan, which is more expensive than the original eggs, so it is not cost-effective for Li Ming to buy two boxes of eggs.

(2) Suppose Zhang Xin bought X boxes of special eggs, 12x= 14x*2-96.

Solution: x=6

So Zhang Xin bought six boxes of discounted eggs. six

A box contains 30 * * * 6 = 180 eggs, so the average daily consumption of eggs in Zhang Xin store is 180/ 18= 10, which will not be wasted.

3( 1). Obviously, Lili is more than 3 kilometers away from her grandmother's house. She walked 3km with 8 yuan, and then walked (17.6-8)/ 1.6 = 6km, so the distance from Lili's house to her grandmother's house is 3+6 = 9km.

(2) If Miss Wang uses one-way billing, it needs *2=25.6 yuan, and if she uses one-time billing, it needs 8+(3+6)* 1.2= 18.8 yuan, so it is more economical to use one-time billing.