Step-by-step explanation: To find the angle they're talking about, angles are always named with the pointy part in the middle.
So angle PRS is the angle with the pointy part at R and one side goes to P and the other to S, kind of like the middle letter is an elbow.
Once you know the angle they're asking for, you got it. Just add up the smaller angles that comprise the larger angle. In the third problem, even though they only give you one of the smaller angles, it id marked as a right angle so you know it's 90.
