y = 8 - 2x
3y = x + 3
3(8 - 2x) = x + 3
24 - 6x = x + 3
24 - 3 = x + 6x
21 = 7x
x = 3
y = 8 - 2 * 3 = 8 - 6 = 2
Ответ: x = 3, y = 2