Let mA = 40°. If B is a complement of A, and C is a supplement of B, find these measures.

If B is a complement of A this means that the sum of the measures of A and B is 90 degrees.

mA + mB = 90

mB = 90 - mA

mB = 90 - 40 = 50

Thus, the measure of angle B is 50 degrees.

If C is a supplement of B then, the sum of the measures of B and C is 180 degrees.

mC + mB = 180

mC = 180 - mB

mC = 180 - 50 = 130

Therefore, the measure of angle C is 130 degrees.