Answer:
x=40
Explanation:
The angles of both expressions (4x-28) and (3x+12) are congruent (alternating exterior angles). So, you can set up the equation 4x-28 = 3x+12 because both expressions are equivalent, so it makes sense. Then solve for x.
4x - 28 = 3x + 12
x - 28 = 12
x = 40