Question

A banked circular highway curve is designed for traffic moving at 65 km/h. The radius of the curve is 207 m. Traffic is moving along the highway at 43 km/h on a rainy day. What is the minimum coefficient of friction between tires and road that will allow cars to negotiate the turn without sliding off the road?
I can't figure this problem out. Any help (formulas, solutions, etc.) would be very much appreciated. Thanks!