$$\left. \begin{array} { l } { ( 2 a ^ { 2 } - 5 ) = 15 } \\ { ( 2 a + 2 ) ( 2 \cdot \frac { 3 } { n - 2 } + 1 - 5 ) = 16 } \\ { n + 2 ) ( } \end{array} \right.$$
