#### Answer

$m=85\frac{1}{3}$

#### Work Step by Step

1. This ratio is the long leg over the hypotenuse for each of the two triangles. Don't fotget that you need to do some addition to get the long leg of the larger triangle
$\frac{75}{80}=\frac{5+75}{m}$
2. Solve for m:
$\frac{15}{16}=\frac{80}{m}$
$15m=1280$
$m=85\frac{1}{3}$