The number could be several different ones. Are you sure that's exactly what the problem says? If not, I'm going to ask you write the entire problem. If not, then whoever made it did not give enough information for there to be an absolute answer. I'm sorry I couldn't help you, but I really hope I can with more information.
He put in the value of x into y
and the value of y in x
if that confuse you here this is what it will look like
(x,y)->(y,x)
Answer:
x=60°
Does the answer help you?
