\[ \frac{3(6y+7)}{12} + \frac{4(8-5y)}{12} = 5 \]
\[ \frac{18y + 21 + 32 - 20y}{12} = 5 \]
\[ \frac{-2y + 53}{12} = 5 \]
\[ -2y + 53 = 60 \]
\[ -2y = 60 - 53 \]-2y = 7y = -3.5
Ответ: y = -3,5