Remember the properties of logarithms. If you have ln81, you can pull out the power of two (9^2) and have 2ln9. Also, you could do ln9 + ln9 because 9*9=81 and ln9*9 = ln9 + ln9
With these properties, you can get 3lnx+2lny, which is 3u+2v according to the answer.
Hope I helped!
did you get the answer yet?