a) 3x - 6 = 12
3x = 12 + 6
3x = 18 /:3
x = 6
b) 5x - 2 = 22
5x = 22 + 2
5x = 24 /:5
x = 24/5
x = 4 i 4/5
c) 2x - 7 = 21
2x = 21 + 7
2x = 28 /:2
x = 14
d) 9x - 5 = 13
9x = 13 + 5
9x = 18 /:9
x = 2
e) 4x + 9 = 17
4x = 17 - 9
4x = 8 /:4
x = 2
f) 6x + 4 = 16
6x = 16 - 4
6x = 12 /:6
x = 2
g) 7x + 5 = 19
7x = 19 - 5
7x = 14 /:7
x = 2
h) 3x + 6 = 24
3x = 24 - 6
3x = 18 /:3
x = 6