summation of the three values

I think something like this would do (I mocked this together to illustrate the idea - you would have your actual events there):

[attachment=0:1t7xmqe4][/attachment:1t7xmqe4]

Since the TotalAttack only changes any time you change equipment you only need to sum the values when that happens.

Then, when you attack something use the TotalAttack global variable to subtract the damage.

Somebody its working every time when i change for example Attack2, suppose that Attack1 and Attack3 its not changed this duplicate with every change i remember when i do something similiar did you check this in practice?

Each time you change one of the three variables ( attack1, attack2, attack3 ), set variable totalAttack=attack1+attack2+attack3

Each time you hit an enemy, set enemyHealth=enemyHealth-totalAttack

So what's the issue?