Suppose angle a is complementary to angle b, and angle b is supplementary to angle c. if measure of angle a is 21 degree, find measure of angle c.

C = 111 degrees

Since A and B are complementary they add to 90. So we know that B must be 69 degrees. 

Since B and C are supplementary they add to 180. So we know that C must be 111. 

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