a)
x - 5 + 6 * x = 16
x - 5 + 6x = 16
x + 6x = 16 + 5
7x = 21 | : 7
x = 3
b)
5 - 2 * x = 9 - 6 * x
5 - 2x = 9 - 6x
-2x + 6x = 9 - 5
4x = 4 | : 4
x = 1
c)
5 * x - 3 + 2 * x = 4 * x + 9
5x - 3 + 2x = 4x + 9
5x + 2x - 4x = 9 + 3
3x = 12 | : 3
x = 4
