How to simplify this expression?

(12^15+12^30-12^49)/(-12^28+12^47-(144^6)/12)

Express the answer as 12^?.

Hint: You have to factor 12^? from the top or bottom so that the expression becomes x/(12^?)(x) or (12^?)(x)/x. Then the x should cancel out, and you get 12^? as the answer.

Thanks!!