I was asked to find a value of R2 to make the diode current = .25 mA on a recent quiz. I breezed through most of the quiz and thought it seemed extremely simple but completely hit a wall with this question and tried everything I knew including node and mesh analysis which usually works for me but everything I did resulted in me having too many unknowns since the value of R3 isn't given. I ran out of time after trying for an hour and a half on this and it is still bugging me a day later. Can someone explain this to me, because it seems very difficult in comparison to the rest of the quiz so I must be doing something very wrong. Thanks in advance.