A rough value of deceleration of a skidding automobile is about 7.0m/s. Using this how long does it take for a car going at 30m/s to stop after the skid starts. How far does the car go in this time.
v = 30 - 7t
so it takes t = 30/7 seconds to stop
s = vt - 1/2 at^2
so plug in your numbers