Hi guys, I'm trying to sort out the following formula, but just can't find out how to solve for 'x'. Could you guys please help me out?? http://imageshack.us/a/img198/4850/screenshot20120917at725.png [Broken] Uploaded with ImageShack.us And I have another one, is there a quick way to solve this one using the log function of a simpele Casio Fx82ms calculator? http://imageshack.us/a/img842/7760/screenshot20120917at731.png [Broken] Uploaded with ImageShack.us The 'x' here is the interest rate and the 'e' mentioned here is the mathematical constant (or 2.71828). I would really appreciate your help!