Explicação passo-a-passo:
a) 3x-10 + 50 + x+20= 180
4x +60 = 180
4x = 180 -60
4x = 120
x= 120/4
x= 30
b) 5x+30 + x +30= 180
6x + 60 = 180
6x = 180 -60
6x = 120
x= 120/6
x = 20
c) 5x -20 = x+20
5x - x = 20 +20
4x = 40
x= 40/4
x= 10
d) 3x +30 +2x +10 = 90
5x + 40 = 90
5x = 90 -40
5x = 50
x= 50/5
x= 10
e) 2x+10 +3x -20= 90
5x - 10 = 90
5x = 90+10
5x = 100
x= 100/5
x= 20
f) x/2 +20 +30= 180
x/2 +50 = 180
x/2 = 180-50
x/2 = 130
x= 130 . 2
x= 260
