a) x + 3 = 2x / - 3
x = 2x - 3 / - 2x
x - 2x = - 3
- x = - 3 / : (- 1)
x = 3
b) 3x = x + 16 / - x
3x- x = 16
2x = 16 / : 2
x = 8
c) 4x - 20 = 8 / + 20
4x = 8 + 20
4x = 28 / : 4
x = 7
:)
