Group - category discount - show percent and price

[Juhy]

Hi,

 

i set a category discount for default group. For example: -50% for iPad category.

I would like to display the category reduction percent (50%) and origninal price on all products, that are in reduction category. (i attached prnScr)

 

Any idea? i looked in product classes but its very complicated system

 

thnx for all tips and help. (i don't whant to use any module)

 

i have prestashop v1.4.4.1