An Automobile's Brakes Are Applied at Time T = 0

Short Answer

An automobile's brakes are applied at time t = 0 when the vehicle is traveling at 48 ft/sec. The brakes cause the automobile to decelerate so that after t sec the velocity is given by v(t ) = 48 - 16t. At what rate is the vehicle decelerating after 1 sec?
Enter just an integer, no units.