The answer is C
First u have to figure out which side is the right angle that equals to 90 after that the opposite angle of the right angle is always the smallest angle so C it will be 30 and the angle above the right angle the number should be between 90 and 30 in this case so the 60 and if u add them it always should give u 180 so 90+60+30=180
Hope that helps !!!