Find the time required for the machine to decelerate to 100 mph in standard air.

A dragster weighing 1600 lbf attains a speed of 270 mph in the quarter mile. Immediately after passing through the timing lights, the driver opens the drag chute of area A=25ft 2 . Air and rolling resistance of the car may be neglected. Find the time required for the machine to decelerate to 100 mph in standard air.