Question:
If $\left(\begin{array}{cc}3 & -2 \\ 5 & 6\end{array}\right)+2 A=\left(\begin{array}{cc}5 & 6 \\ -7 & 10\end{array}\right)$ then $A=?$
A. $\left(\begin{array}{cc}1 & 3 \\ -5 & 4\end{array}\right)$
B. $\left(\begin{array}{rr}-1 & 5 \\ -3 & 4\end{array}\right)$
C. $\left(\begin{array}{cc}1 & 4 \\ -6 & 2\end{array}\right)$
D. none of these
Solution:
$\mathrm{C}$
