Suppose triangle a b c is similar to triangle p q r. also, angle a measures 45° and angle b measures 60°.

It looks like you are missing the question here. Most of the time in this type of questions, we are looking for the 3rd angle.

Let's assume that you need the 3rd angle.

There are 180 degrees in a triangle. We know 2 of the angles, so by subtracting them from 180 we can find the 3rd angle.

180 - 45 - 60 = 75

Angle C is 75 degrees. In the similar triangle Angle R is also 75 degrees because the corresponding angles are congruent.