Уравнение:
0.4(2y - 5) = 2.8(y + 4) + 7.4
0.8y - 2 = 2.8y + 11.2 + 7.4
0.8y - 2 = 2.8y + 18.6
-2 - 18.6 = 2.8y - 0.8y
-20.6 = 2y
y = -10.3