Answer:
x = 20
Step-by-step explanation:
The angles 7x° and (x + 20)° are supplementary angles.
Supplementary angles add up to 180°.
Therefore we have the equation:
7x + (x + 20) = 180
7x + x + 20 = 180 subtract 20 from both sides
8x = 160 divide both sides by 8
x = 20
