Bonjour,

1)

5x-20 = -3x -36

5x+3x = -36 +20

8x = -16

x = -16/8

x = -2

2)

-6+76 = 4x +3x

70 = 7x

x 70/7

x= 10

3)

3x+4x = 26+9

7x = 35

x= 35/7

x= 5

4)

3x+27 = -x +27

3x+x = 27-27

4x = 0

x= 0