Find the discount taking into account the qty ordered

Hello,
I need your help. I need to find a formula for column B, to find the right discount(from C:I) taking into account the qty ordered.
If all the columns where filled in, it had been easier . But if there where spaces( few packages lets say) , I see the discount 0 and is not correct.
Hope I make myself clear.

Thanks for your help.
C

not quite clear
how to choose a column?

for example line 3: if the qty ordered is 4 , than is less than 5 , means we need to look at the discount from column C, if the qty would be 5, we should look at the blue columns ,the discount from E, etc.
but some lines (lets imagine there are products) dont have all the 3 packages. for the last one , for ex, we offer 10% regardless.
is now ok??

Hi , I have explained bellow, not at this post, soorry

attempt 2: why C or E or I

Originally Posted by tim201110

attempt 2: why C or E or I

you pick C or E or G,I taking into account the qty that is ordered - column A!