Question

Start from 110 feet away, a person on a bicycle rides toward a checkpoint a nd then passes it. The rider is traveling at a constant of 30m feet per second. The distance between the bicycle and the checkpoint is given by the equation d=(110-30t). At what times is the bike 40 feet away from the checkpoint?

My answer is 2.3 seconds for the beginning but I'm not sure if the last number is 4.6 seconds or 5.0 seconds