Answer:
It is indeed 63
Explanation:
The easy way to go about this is to recognize that if the triangles are similar, the ratio between the similar sides will be the same.
Notice:
4/5 = 36/45
So:
4/7 should = 36/x
If:
4/7 = 36/x
4x/7 = 36
4x = 36*7
x=36*7/4
x=63