At an accident scene on a level road, investigators measure a car's skid mark to be 88 m long.?

At an accident scene on a level road, investigators measure a car's skid mark to be 88 m long.?It was a rainy day and the coefficient of friction was estimated to be 0.42. Use these data to determine the speed of the car when the driver slammed on (and locked) the brakes.Answer in m/s. Also, Why does the car's mass not matter?