The correct factors are \( p = 17 \) and \( q = -20 \).
\[
\begin{array}{|c|c|c|}
\hline
\boldsymbol{p} & \boldsymbol{q} & \boldsymbol{p + q} \\
\hline
10 & -35 & -25 \\
\hline
-10 & 35 & 25 \\
\hline
50 & -7 & 43 \\
\hline
-50 & 7 & -43 \\
\hline
17 & -20 & -3 \\
\hline
\end{array}
\]
\(\boxed{p = 17, \, q = -20}\)