{math} not working on prestashop 1.7.5

[MyDesignAr]

hi, i'm trying to show a simple math result into my miniatures/product.tpl but is not working.

The code i'm using is:

{* $height=4, $width=5 *}
{math equation="x + y" x=$height y=$width}

The above example will output 9... 

Some help? Thanks!

[Rolige]

Hello:

You can't just copy directly from smarty doc. This is a comment {* $height=4, $width=5 *}  not a variable declaracion. $height and $width must be defined before operation. Try with static values or a defined variable.

Regards