I have a nprice to calculate
unit cost 15 euros
the discount is calculated on the basis of - (ncost * percentage/ 100)
But I not Know the right percentage to insert
I tried with 10,12 and 13 but it not run ok
sample :
if it costs 30 euros the percentage discount makes me 28.05 while it should be 25 for 2 products ( perhaps -5)
if it costs 45 euros the percentage discount makes me 41.10 while it must be 40 for 3 products ( perhaps -5)
if it costs 60 euros the percentage discount makes me 54.15 while it should be 50 for 4 products ( perhaps -10)
if it costs 75 euros the percentage discount makes me 67.20 while it should do 60 for 5 products ( perhaps - 15)
How I can calculate the exactly percentage ?
any solution ?