Hello everyone
I'm making a sort of calculator with fields that I activate or not. Which works perfectly.
But to do it well, I want if I hide a text box containing a sum, it is not included in the result.
Is it possible ?
Thank you all
Number of prices ? {formmenu: default=0; 1; 2; name=prices}
{if: prices = "1" OR prices = "2"}{formtext: name=pricedollars1; default=50}${endif}
{if: prices = "2"}{formtext: name=pricedollars2; default=50}${endif}
Total {=pricedollars1 + pricedollars2}$
Not sure I fully understand this, but it sounds like you want something like:
Number of prices ? {formmenu: default=0; 1; 2; name=prices}
{if: prices = "1" OR prices = "2"}{formtext: name=pricedollars1; default=50}${endif}
{if: prices = "2"}{formtext: name=pricedollars2; default=50}$
Total {=pricedollars1 + pricedollars2}${endif}
Not that 
If i select one price, the total take the first text box.
If i select the second price, total count the first and second text box.
but if I change my mind, i choose only one text box, i do not want box number 2 where I entered an amount to be counted
I hope that it's clearer.
Is this what you're looking for?
Number of prices ? {formmenu: default=0; 1; 2; name=prices}
{if: prices = "1" OR prices = "2"}{formtext: name=pricedollars1; default=50}${endif}
{if: prices = "2"}{formtext: name=pricedollars2; default=50}${endif}
{counted1=pricedollars1 if prices="1" or prices="2" else 0}
{counted2=pricedollars2 if prices="2" else 0}
Total {=counted1 + counted2}$
Ho yeaaaaaaaaaaaaaaaa 
Perfect