\[x^{2} - 7x + q = 0;\ \ \ \ x_{1} = - 3\]
\[( - 3)^{2} - 7 \cdot ( - 3) + q = 0\]
\[9 + 21 + q = 0\]
\[q = - 30.\]
\[x^{2} - 7x - 30 = 0\]
\[x_{1} + x_{2} = 7\]
\[- 3 + x_{2} = 7\]
\[x_{2} = 10.\]
\[Ответ:\ \ x_{2} = 10;\ \ q = - 30.\]