Explain how an aiirbag responds to an impact and if possible link it to a mathematical relationship
Airbags increase the impact time in the collision between the passenger/driver and the car. This reduces the force experienced by the passenger/driver. You can link this to Newton's second law: force = mass x acceleration. Acceleration is the rate of change of velocity, the passenger slows down over a longer period of time, decreasing the acceleration, which thus reduces the force experienced by the passenger.
Alternatively, you can link it to an alternative form of f=ma, which is force = change in momentum/time and argue how a greater impact time decreases the force experienced, because you are dividing by a greater number.