I was thinking to formulate some equation based on EV to know what range of hands I can go all in preflop to resteal the pot, when someone have already raised before.

And I wrote something like that in a paper:

EV = FE (POT) + (1 - FE).[E*(BB+SB+ANTES+STACK) + (1-E).STACK]

FE = I named by Fold equity the times that the villain folds, I don't know if it is the correct name.

(1-FE) = When Villain Calls

E = Equity, Chance I have to win the hand when he calls

(BB+SB+ANTES+STACK) : How much I win when I win. I sum with stack because villain should put my stack into the table to make a call.

(1-E) = Chance that I have to loose the hand

Stack = What I will loose

If EV = 0 and IF I know the fold equity of the villain, I can find the value of equity.

So I saw some calculator on internet to calculate fold equity, but how is it calculated ? based on my stack I think and how much is already in the pot.

If I know the equity necessary to make EV=0 I think I can make a range based on his call range.

I don't know if what I'm thinking is correct, if someone can give me a help I will appreciate.

EV = FE (POT) + (1-FE)[E*(BB+SB+ANTES+STACK) - (1-E)STACK]

I think you flipped one sign.