Answer:
A measures 72 and B measures 108
Step-by-step explanation:
If the angles are supplementary, that means that they add up to equal 180. 3x + 12 + 4x + 28 = 180. Doing some algebra there gives you that 7x = 140 and x = 20. Sub in 20 to angle A to get 3(20) + 12 = 72, and sub in 20 to angle B to get 4(20) + 28 = 108. And of course, 108 + 72 = 180.
