Angle b measures 60°. what is the measure of angle that is complementary to angle b?

Since a complementary angle is two angles that equal 90 degrees the compliment of angle B would be 30 degrees since 60+30 = 90.

Solutions 

Complementary angle are two angles whose sum is 90°. We know that Angle b measures 60°. 

60° + (X) = 90° 

90° - 60° = (X) 

90° - 60° = 30° 

(X) = 30° 

30° complementary to Angle B