$\left[\begin{array}{cc}\mathit{a}-\mathit{b}& 2\mathit{a}+\mathit{c}\\ 2\mathit{a}-\mathit{b}& 3\mathit{c}+\mathit{d}\end{array}\right]$ = $\left[\begin{array}{cc}-1& 5\\ 0& 13\end{array}\right]$
Equating the corresponding elements, we get,
⇒ a - b = -1, 2a + c = 5, 2a - b = 0, 3c + d = 13
Now, consider the equations:
a - b = -1 and 2a - b = 0
Subtracting first equation from second, we get: a = 1