C

C

B

1

C

D

1

C

A

50-8x=38

Solution: (1) Let this number be x, and the equation:1x-3 = 9 in 7.

(2) Let the side length of the original square iron sheet be x cm. Equation: x squared -2x=80

(3) Suppose Uncle Wang needs X months to pay off all the payment. Equation: 3000 ten 1500x= 19500.

12.A

13.B

14.( 10-x)，3x 15 ( 10-x)=40-2，6

15.( 1). Solution: If you buy x articles, you will buy (15-x) information newspapers. Equation: 0.5x10.4 (1.5x-x) = 7.

(2) If X adult tickets are sold, (128-X) student tickets will be sold. Equation:10x10 (128-x) x10x60% = 912.

16.( 1)6.

(2)3

17.m=4，n= 1

18.( 1). Solution: The phone bill payable by mode A is 0. 15x, and that payable by mode B is (18 10. 1x).

(2) One yuan at a time.