48.59° is your answer.
Soh Cah Toa
Looking at the unknown angle, you know the opposite angle(45) and the hypotenuse(60). Opposite and hypotenuse is Soh which is sin.
Sinx = 45/60(opposite/hypotenuse)
(sin-1*)sinx = 45/60 (*sin-1) ----multliply by sin-1 (inverse)
The sins cancel leaving you with...
x = sin-1(45/60)
If you plug that into a calculator you should get about 48.59°.