The second one solves for the forward premium or forward discount. I think many traders use quotations based on premiums or discounts on the spot exchange rate, so this formula may be used commonly.

Thank you for your response but I’m still lost =( How did you get -1 in the second line? And how did (1+id) end up in the numerator in line 3? I really hope I am not recalling some simple math formulas from that I haven’t used in years. Your help is much appreciated!