Distance is speed or velocity multiplied by time: d = v * t
We know the speed of the car and the time it travelled, so input the two into the equation above and solve for the distance travelled.
d = v * t
d = 64 m/h * (5 hours and 15 minutes) = 64 m/h * (5.25 hours)
d = (64 * 5.25) miles
d = 336 miles
