Respuesta :

Step-by-step explanation:

1)3(x+15)=57

3x+45=57

3x=57-45

3x=12

x=12/3.

x=4

2)2(x-9)=26

2x-18=26

2x=26+18

2x=44

x=44/2

x=22

3)4(x-12)=-32

4x-48=-32

4x=-32+48

4x=+16(greater number sign)

x=16/4

x=4