\[7y^{2} + 50y + 86 = 0\ \ \ \ \]
\[D = 625 - 602 = 23\]
\[y_{1,2} = \frac{- 25 \pm \sqrt{23}}{7};\]
\[x_{1} = 3 \cdot \left( \frac{- 25 - \sqrt{23}}{7} \right) + 10 =\]
\[= \frac{- 75 - 3\sqrt{23} + 70}{7} =\]
\[= \frac{- 5 - 3\sqrt{23}}{7}.\]
\[x_{2} = 3 \cdot \left( \frac{- 25 + \sqrt{23}}{7} \right) + 10 =\]
\[= \frac{- 75 + 3\sqrt{23} + 70}{7} =\]
\[= \frac{- 5 + 3\sqrt{23}}{7}.\]