Answer
$$(m+13)(m-5)$$
Work Step by Step
Since the coefficient of the squared term is one, we know that the expression must factor to:
$$ (m\pm a)(m\pm b)$$
Here, we see that a and b must multiply to get $-65$ and add to get $8$. Thus, we find that the solution is:
$$(m+13)(m-5)$$