Can anyone help with this problem?

ln(r^3s^7([7th root](r^7s^10)))

is equal to A ln r +B ln s

where A=______ and B=________

This is what I have so far:

3 ln r + 7 ln s + 7th root (r^7s^10)

I thought it should be

3 ln r + 7 ln s + 49/2 ln r + 70/2 ln s=

55/2 ln r + 84/2 ln s

but that is wrong. How do you do the 7th root?