Question

por favor me ajudem nesse dever
$7x + x - 20 = 2x + 70$
$3x + x - 2 + 15 - 20 = x - 30$
$4x + 70 - 20 + 2x = x - 17 + 100$
no final é +100

Answer 1

7x+x-20=2x+70
8x-20=2x+70
8x-2x=70+20
6x=90
x=90/6=15

3x+x-2+15-20=x-30
4x-7=x-30
4x-x=-30+7
3x=23
x=23/3

4x+70-20+2x=x-17+100
6x+50=x+83
6x-x=83-50
5x=33
x=33/5