\[2(5x - 4y) - 3(4x - y) =\]
\[= 10x - 8y - 12x + 3y =\]
\[= - 2x - 5y;\ \]
\[x = - 5;\ \ y = 0,8:\]
\[- 2 \cdot ( - 5) - 5 \cdot 0,8 = 10 - 4 = 6.\]
\[Ответ:6.\ \]