Two angles are supplementary. the first angle measures 60°. what is the measurement of the second angle?

Two angles are supplementary when the first angle measure 60° and the second angle measures 120°.

Supplementary angles are called such when the measurement of both angles add up to 180°.

In the above question, since the first angle is 60°, you must deduct it from 180° to make the second angle supplementary to the first angle; resulting to the second angle having a measurement of 120°