3x + 6 = 12
2x = 8
4x + 3 = 21 - 2x
2(3x - 2) = 2
3(1 + 2x) = 36
3(x - 7) = 5(x - 1) - 4x
x = 3
x = 8
x = 5
x = 2
x = 1
