(2) Xiao Wang: a+2, Xiao Chen: a+2-3=a- 1.

4.x*5=5x yuan. When x=4, 5x=5*4=20 yuan, and it should be returned as 30-20= 10 yuan.

x+ 15=20 x=20- 15 x=5

7x=56 x=56÷7 x=8

80-x=76 x=80-76 x=4

x÷ 1.5=4 x=4* 1.5 x=6

x+ 1.5 = 4 x = 4- 1.5 x = 2.5

x- 1.5 = 4 x = 4+ 1.5 x = 5.5

Remember to adopt it as the best.