Which graph represents an exponential function? On a coordinate plane, a curve decreases rapidly and then levels out.
On a coordinate plane, a curve decreases, changes directions, and then decreases again.

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.