Hello. I'm new at odoo. I need to add a percentage field (10% or editable) to the supplier's order and create an order for this quantity.

For example

I am just create new variables in odoo

x_discount_new

x_product_qty_new

x_product_qty_new_int

How do I implement the task?

Need to calculate 

x_product_qty_new=product_qty+product_qty*discount_new/100

product_qty_new_int=int(product_qty_new)

price_subtotal=product_qty_new_int*price_unit

Thank you.