I got the idea.

5(90 - x) = 2(180 - x)

450 - 5x = 360 - 2x

90 = 3x

30 = x

180 - 30 = 150

Why would i get a different answer is I set it up as

5(180 - x) = 2(90 -x) ?

What is the key part in the question that makes our expression be 5(90 -x) = 2(180 -x)