Question 50106
Your answer to part a is correct. With part b, you're on the right track, but it can be simplified even more:

Sqrt(64x^5)/Sqrt(121x^7)
8Sqrt((x^4)x)/11Sqrt((x^6)x)
(8x^2)Sqrt(x)/(11x^3)Sqrt(x)
(8x^2)/(11x^3)
8/(11x)

Good work and good luck in your class!