Systems, Matrices, and Determinants · Medium problem

Solve $2X=A-B$ for the matrix $X$, where $A=\begin{bmatrix}5&1\\3&7\end{bmatrix}$ and $B=\begin{bmatrix}1&-1\\0&2\end{bmatrix}$. Find the entry of $X$ in row $1$, column $2$.