A problem rather tricky...Please help me (not so much as GRE.but still college mathematics)

A turn-of -the-century bicycle has a front wheel with a diameter of 6 feet and a back wheel

with a diameter of 2 feet. When the bicycle rolls 600 PI feet in a straight line,

a. How far does a point on the tread of the back tire travel?

b. How far does a point on the tread of the front tire travel?

Justify your answers to (a) and (b).