Kits and sales

HI, I am interested in getting the Firewall Kit in the sales on Sunday (50% off Turrets and Paints) and I am wondering how much that kit would be then. I know there is math behind it, not just adding the percents, and I don't know how to do it because the Wiki Page doesn't give that information (http://en.tankiwiki.com/Product_kits). It says "All discounts, including the kits' discount, are not added to each other but act as multipliers. For example, if you got 40% off for a kit and 30% off for the turret in that kit, the total discount will be 58% for the turret and 40% for the other items in the kit." I would like to know that information on the Firewall Kit (Firebird M2, Hunter M2, Hohloma, Grizzly-T-E M2. Could someone tell me how expensive this kit will be in total when its Turret and Paint are at 50% off? Thanks!