[SOLVED] Need help with pulley problem

Hi, i need help with the following question:

The sprocket assembly for a

0.800 m diameter bike wheel is

shown here. If the rider can

pedal at 50.0 rotations per

minute, what speed will the bike

be traveling? Express your

answer in km/hr. The radius of

the back sprocket is 0.050 m

and the radius of the front

sprocket is 0.150 m.

Here is the picture for reference:

[html]http://img191.imageshack.us/i/33012387.png/[/html]I don't know how to start this question, but i do know that the velocity of the pulley or sprocket is the same.