Complementary angles are angles whose sum is 90 degrees.
If angle AOB and angle BOC are complementary and angle AOB is x degrees, it means that angle BOC is (90 - x) degrees
Supplementary angles are angles whose sum is 180 degrees. If angle BOC is (90 - x) degrees, then the measure of its supplement would be
180 - (90 - x)
= 180 - 90 + x
= 90 + x
the measure of the supplement of angle BOC is (90 + x) degrees
