Answer:
x = 30
Explanation:
∠QUT and ∠SVW are in a way, essentially supplementary angles. In other words, if you added both of the angles together, it would equal 180° which is a line. So,
x + 12 + 3x + 48 = 180
Solve for x by combining like terms :)
x + 12 + 3x + 48 = 180
4x + 60 = 180
4x = 120
x = 30