Question

I really need help. I can't find the answer to both math problems.

Answer 1

I'm not sure about the second one, but the first one would still be 72 degrees.

When it comes to similar triangles, even if one of the triangles are bigger, the angle measures stay the same. The side lengths are what will change.

Answer 2

1)   72 degrees. In similar shapes angles are the same, but not side lengths

2) 7.5  The side lengths have the same ratio to each other in similar shapes 

$\frac{2.5}{n} = \frac{5}{15}$
5/15 simplifies to 1/3
$\frac{2.5}{n} = \frac{1}{3}$
cross multiply 
n=7.5