Trigonometry · Superchallenge problem

A spool consists of a hub of radius $2$ cm between two end rims of radius $5$ cm. The rims rest on a table. A string wound around the hub leaves from the BOTTOM of the hub and runs horizontally to your hand. You pull the string horizontally, and the spool rolls toward your hand without slipping. When your hand has moved $30$ cm, how far has the spool's axle moved, in cm?