Simple Microscope Problem that I have been STUCK on!!! 1. The problem statement, all variables and given/known data How far from a lens of focal length 50 mm must the object be placed if it is to form a virtual image magnified in size by a factor of 3? 2. Relevant equations 3. The attempt at a solution I thought I could us the equation... M = s'-f/f to get s' and then use... 1/f = 1/s + 1/s' to get the object distance but I am not coming up with the right answer??