18°
Step-by-step explanation:
Find the diagram attached
From the diagram, since the opposite side are parallel, the sum of the adjacent angle is 180 degrees
From the diagram, m<RQP + m<QPO = 180
Given
m<RQP = 6x+9
m<QPO = 63
Substitute
6x+9+63 = 180
6x + 72 = 180
6x = 180 - 72
6x = 108
x = 108/6
x = 18 degrees
Hence the value of x is 18°