\[\text{M\ }(3;\ - 5);\ \ y = kx - график\ \]
\[прямой\ пропорциональности.\]
\[- 5 = 3k\]
\[k = - \frac{5}{3} = - 1\frac{2}{3}.\]
\[Формула:\ \ y = - 1\frac{2}{3}\text{x.}\]