Answer:
The angles are 81 degrees and 99 degrees
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Step-by-step explanation:
Consecutive angles, aka adjacent angles, of a parallelogram always add to 180 degrees. They are considered supplementary.
(angle A)+(angle B) = 180
(3x+42)+(9x-18) = 180
(3x+9x)+(42-18) = 180
12x+24 = 180
12x = 180-24
12x = 156
x = 156/12
x = 13
We can then find the measure of each angle
- angle A = 3x+42 = 3*13+42 = 81
- angle B = 9x-18 = 9*13-18 = 99
Then notice that A+B = 81+99 = 180 to confirm the answers.