Ответ:

6.4-0.5у-4.5=1-0.5у

-0.5у-0.5у=1+4.5-6.4

у=-0.9

[tex]6.4 - 0.5(y - 9) = - 0.5(2y) \\ 6.4 - 0.5y + 4.5 = - 0.5 \times (2y) \\ 6.4 - 0.5y + 4.5 = - 0.5 \times (2y) \\ 10.9 - 0.5y = - 0.5 \times 2y \\ 10.9 - 0.5y = - y \\ - 0.5y = - y - 10.9 \\ 0.5 y+ y = - 10.9 \\ 0.5y = - 10.9 \\ y = 21.8[/tex]