Hi. I've been trying to understand the solution to a practice problem in my book (it only provides the answer), but I cant seem get it. The problem gives the circuit in the attachment and asks the following: Find a value of R such that V0 is equal to 2.4 V. Assume that the diodes available have 0.7 V drop at 1 mA. The solution is R = 139 ohms. I keep getting about 160. If someone could tell me how I should go about solving this it would be great! Thanks.