There are a couple different ways to word this, but the easiest would be by using alternate exterior angles. This means that the angle of the Pizza Palace and the angle under the Shake Hut are congruent.
54 = 54
You also know that because 6th and 7th are parallel, the 54 angle and the Shake Hut are supplementary, meaning they add up to 180 degrees.
So to find the angle of the Shake Hut, all you do is subtract 54 from 180.
180-54 = 126
So the answer is C. 126.