Question

This is the question and i need to know the formula and the steps.."A car's airbag will activate and increase the stopping time of a passenger from 1.0 x 10-2s to 3.0 x 10-1s. If the person in the car has a mass of 70.0kg and the car is travelling at 100km/h (approximately 28 m/s), determine the magnitude of force that the person will exert on the airbag. I am not the greatest with this kind of thing so any help is much appreciated..