I'll just ask a portion of the question:
How does the fractional exponent in (3/7)9^(7/3) simplify to 384/7 and how does (3/4)9^1/3 simplify to [I don't know the answer to this... it's either 12, 3/7, or 3/4]?
I'd understand it if the exponent was a square root, but with a cube root, I'm lost.