Array sum question

Hello everybody, I have a specific question and I hope I'll be as clear as possible:

In my game, I have several levels. For each level you pass, you gain a certain amount of XP. Then, I want the sum of those XP's to show in the level screen.

Example: XP_total = levelxp1 + levelxp2, and so on.

I did that with the "For each X element" >> Add levelxp.CurValue to XP_total" .

I already managed to do that perfectly, but here comes my problem: I want to implement some boosters to buy with the XP you gain.

Example: Booster "Nitro" costs 50 XP. So, I subtract the 50 XP from XP_total. But, when I go back playing the game, it re-calculates the sum of all levelxp's, and it forgets the subtraction I did.

I already tried to create another instance variable that is equal to XP_total, but it doesn't work properly.

If somebody could help me, it'll be very much appreciated!

Bump! And what the hell is with the chinese character posts spam!!

Would creating three global variables work?

CombinedXP : set to the "For each X element" >> Add levelxp.CurValue to CombinedXP"

BoosterCosts : set to the amount of XP spent on boosters

XPtotal : set to combinedXP minus Boostercosts

Would creating three global variables work?

CombinedXP : set to the "For each X element" >> Add levelxp.CurValue to CombinedXP"

BoosterCosts : set to the amount of XP spent on boosters

XPtotal : set to combinedXP minus Boostercosts

I'ma try this and give you my feedback, thank you!