1. A car is moving along a straight horizontal road at a constant speed of 18ms^-1. At the instant when the car passes a lay-by, a motorcyclist leaves the lay-by, starting from rest, and moves with constant acceleration 2.5ms^-2 in pursuit of the car. Given that the motorcyclist overtakes the car T seconds after leaving the lay-by, calculate

a) the value of T

b) the speed of the motorcyclist at the instant of the passing the car.

My teacher explained how to do the question, but I really don't understand the workings.