Răspuns:
a) 3(x+7)=12
3x+21=12
3x=21-12=> 3x=9=> x=3
b) -2(x+9)= -28
-2x+(-18)= -28
-2x= -28+18 => -2x= -10 => x=5
c) 5(3-2x)= -10
15-10x= -10
10x= 5 => x=2
