Question

Galileo's first telescope used a convex objective lens with a focal length f = 1.65 m and a concave eyepiece. When this telescope is focused on an infinitely distant object, and produces an infinitely distant image, its angular magnification is +3.11. What is the focal length of the eyepiece?
How far apart are the two lenses?

Please help!? I have been stuck on this problem and I don't know where to begin.
jaykim
fo/fe=3.11 fe=1.65/3.11=0.53m since at infinity,their focal length coincides,d=1.65+0.53=2.18m