Motion with Constant Acceleration

[JustGracie]

1. The problem
A motorcyclist slows down uniformly as he approaches a red light. He takes 3.2 seconds to come to a halt and travels 40m in this time.
How fast was he traveling initially?

Homework Equations

s=(u+v)/2*t

 

[XanziBar]

Any other kinematic equations? If you can find his acceleration, I bet you could find his initial velocity.