Question

13=5x-3
3x+4=5x-7
X+20-3=7

Answer 1

1)15+3=5x
    18=5x
x=18/5

2)4-7=5x-3x
   -3=2x
x=-3/2


3)x=7+3-20
  x=-10

Answer 2

A primeira
13=5x-3
13+3=5x
16=5x
x=16/5
A segunda
3x+4=5x-7
4+7=5x-3x
11=2x
x=11/2
A terceira
x+20-3=7
x+17=7
x=7-17
x=-10
Esses são os valores....