4x + 5y = 170 |·2
3x + 2y = 14 |·5
8x + 10y = 340
15x + 10y = 70
Вычтем из первого второе:
8x - 15x + 10y - 10y = 340 - 70
-7x = 270
x = -270/7
3x + 2y = 14
y = 7 - 1,5x
x = -270/7
y = 7 + 405/7
x = -270/7
y = (49 + 405)/7
x = -270/7
y = 454/7 = 64 6/7
x = -270/7 = -38 4/7
Ответ: (-270/7; 454/7).