Odpowiedź:
5x - 7 = 13
5x = 13 + 7
5x = 20
x = 4
2x + 8 = 20
2x = 20 - 8
2x = 12
x = 6
8x + 4 = 3x + 14
8x - 3x = 14 - 4
5x = 10
x = 2