Help with a little physics question?

A hockey puck is hit on a frozen lake and starts moving with a speed of 10.8 m/s. Five seconds later, its speed is 5.30 m/s. I've calculated the average acceleration as -1.1 m/s^2, and I know that the puck travels 40.25 m during the 5 second interval. Given this information, how would I calculate the coefficient of kinetic friction between the puck and the ice? It would be really helpful if you just explained how to go about solving it, and didn't post an answer. Thanks so much!