Profit Calculator
There’s actually a small little website that will do it for you. tpcalc.com. Punch in the cost of an item, the amount you’re selling it for, and it will take into account the 15% TP fee and tell you how much profit you’ll make (both in raw coins and as a percentage). It’s a handy thing to use on your smart phone while doing business in the TP.
Another useful site is gw2spidy.com, which shows a graph of historical item prices for any and all GW2 items in the TP, so you can get an idea of whether or not a particular price is outrageous or not.
Interesting formula.
You can also get those salvage kits from BL chests. It may be worth it if you have any use for the other boosters.
Edit: wasn’t paying attention to parenthesis