Consider the system of linear equations
\( -x + y + 2z = 0 \)
\( 3x - ay + 5z = 1 \)
\( 2x - 2y - az = 7 \)
Let \( S_{1} \) be the set of all \( a \in \mathbb{R} \) for which the system is inconsistent and \( S_{2} \) be the set of all \( a \in \mathbb{R} \) for which the system has infinitely many solutions. If \( n(S_{1}) \) and \( n(S_{2}) \) denote the number of elements in \( S_{1} \) and \( S_{2} \) respectively, then:
