Solution:
It is determinant multiplied by a scalar number 2 , just find determinant of matrix and multiply it by 2 .
$\begin{array}{l}
2 \times(35-20) \\
2 \times 15=30
\end{array}$
Evaluate $2\left|\begin{array}{cc}7 & -2 \\ -10 & 5\end{array}\right|$.
Evaluate $2\left|\begin{array}{cc}7 & -2 \\ -10 & 5\end{array}\right|$.