posted by Audrey .
Tiffany can run 12 miles in the same time it takes her to bicycle 72 miles. If her bicycling rate is 20mi/hr faster than her running rate, find each rate.
Let X = running rate, so X +20 = cycling rate.
Since rate = miles/time, then time = miles/rate. Since the time for both is the same:
12/X = 72/(X + 20)
You should be able to take it from here.
I hope this helps. Thanks for asking.