jmc

We have that $$\left(\begin{array}{cc}2& 0\\ 5& -3\end{array}\right)\left(\begin{array}{cc}8& -2\\ 1& 1\end{array}\right)=\left(\begin{array}{cc}(2)(8)+(0)(1)& (2)(-2)+(0)(1)\\ (5)(8)+(-3)(1)& (5)(-2)+(-3)(1)\end{array}\right)=\boxed{\left(\begin{array}{cc}16& -4\\ 37& -13\end{array}\right)}.$$