Answer:
x = 21
Step-by-step explanation:
You are given expressions (x+63)° and (4x)° for alternate interior angles at a transversal crossing parallel lines. You want to know the value of x.
Alternate interior angles
Where a transversal crosses parallel lines, alternate interior angles are congruent. That means ...
(4x)° = (x +63)°
3x = 63 . . . . . . . . divide by °, subtract x
x = 21 . . . . . . . . . divide by the coefficient of x
