Precalculus (6th Edition) Blitzer

If $\left[ \begin{matrix} 3 & x \\ y & -7 \\ \end{matrix} \right]=\left[ \begin{matrix} 3 & -10 \\ 6 & -7 \\ \end{matrix} \right]$, then $x=-10$ and, $y=6$
It is given that, $\left[ \begin{matrix} 3 & x \\ y & -7 \\ \end{matrix} \right]=\left[ \begin{matrix} 3 & -10 \\ 6 & -7 \\ \end{matrix} \right]$ The two matrices are equal only when the corresponding elements of both the matrices are equal. That is, \begin{align} & 3=3 \\ & x=-10 \\ & y=6 \\ \end{align} And, $-7=-7$ Hence, $x=-10\text{ and }y=6$