2x+32= 1 152

2x= 1 152-32

x= 1 120÷2

x=560

2) solution: let each pen be x yuan.

3x+2x=40

5x=40

x=40÷5

x=8

3) solution: catch up after leaving x hours.

15x = 12x+ 12×3/4

15x- 12x=9

x=9÷3

x=3