At the Winter Olympics, an athlete rides her luge down the track while a bell just above

Question:

At the Winter Olympics, an athlete rides her luge down the track while a bell just above the wall of the chute rings continuously. When her sled passes the bell, she hears the frequency of the bell fall by the musical interval called a minor third. That is, the frequency she hears drops to five sixths of its original value.
(a) Find the speed of sound in air at the ambient temperature *10.0°C.
(b) Find the speed of the athlete.