An angle measures 15° more than its supplement. What is its measure?

Supplementary angles add up to 180°. We can label the measures of the two angles x and x + 15. The supplementary knowledge that the angles are supplementary gives us an equation.

x + (x + 15) = 180 2x + 15 = 180

Solving this equation yields x = 82.5°. Since the question asks for the larger of the two angles, we plug 82.5 into x + 15 to get 97.5°.