\[\left\{ \begin{matrix} y = - \frac{7}{8}x + 17 \\ y = - \frac{3}{5}x - 16 \\ \end{matrix} \right.\ \]
\[1) - \frac{7}{8}x + 17 = - \frac{3}{5}x - 16\]
\[- \frac{7}{8}x + \frac{3}{5}x = - 16 - 17\]
\[\frac{- 35 + 24}{40}x = - 33\ \ \ | \bullet 40\]
\[- 11x = - 1320\ \ \ |\ :( - 11)\]
\[x = 120.\]
\[2)\ y = - \frac{3}{5} \bullet 120 - 16\]
\[y = - 3 \bullet 24 - 16\]
\[y = - 72 - 16\]
\[y = - 88.\]
\[3)\ y + px = 0\]
\[- 88 + p \bullet 120 = 0\]
\[120p = 88\]
\[p = \frac{88}{120}\]
\[p = \frac{22}{30}\]
\[p = \frac{11}{15}\]
\[Ответ:\ \ при\ p = \frac{11}{15}.\]