1. The problem statement, all variables and given/known data A lens has a focal length of 120 cm and a magnification of 4.0. How far apart are the object and the image? 2. Relevant equations I used the thin lens equation 1/f = (1/di + 1/do)^-1 and M = -d image/d object 3. The attempt at a solution I have been trying this by rearranging the thin lens equation...didnt work. Tried finding di and do given only magnification - cant do with only 1 known variable. I dont think my approach is right at all. Any help will be appreciated.