Can someone help me pls

Which expression do you get when you eliminate the negative exponents of 4a^2 b^216a^-3 b

Solve 4 ln x=2ln25 a) x=5 b) x=25 c) x=625

Martha is training for a duathlon, which includes biking and running. she knows that yesterday she covered a total distance of over 55.5 miles in more than than 4.5 hours of training. martha runs at a speed of 6 mph and bikes at a rate of 15.5 mph.