What is bmatrix 7 & 2 \\ 5 & 9 bmatrix - bmatrix 3 & 4 \\ 1 & 6 bmatrix?

Subtract corresponding entries: $7-3=4$, $2-4=-2$, $5-1=4$, and $9-6=3$, giving $\begin{bmatrix}4&-2\\4&3\end{bmatrix}$, choice F. Choice G has $2$ in place of $-2$, which comes from computing $4-2$ rather than $2-4$ in the top-right position. Choice H adds the matrices instead of subtracting them. Choice J is $B-A$, with every sign reversed, so the order of subtraction is wrong. Matrix subtraction is not commutative, so the first matrix always comes first and the second is subtracted from it.