Find the x in the figure. Assume a and b are parallel

Answer:
x = 15
Step-by-step explanation:
(4x - 30) and (2x) are alternate angles and are congruent , then
4x - 30 = 2x ( subtract 2x from both sides )
2x - 30 = 0 ( add 30 to both sides )
2x = 30 ( divide both sides by 2 )
x = 15