need help with if function

[len2088]

So I need to create an invoice where if you check a check box the value on another cell gets a discount. I want to then add the total of all the discount calculated and display it on a different cell.

I am using this:

SUM(IF(F20="D",(E20*0.1)),IF(F21="D",(E21*0.1))........Etc

I am using "D" ti indicate discount for now because I don't know how to use check boxes but my goal is to use a check box instead of typing "D".
what I want is that after it does the calculation of the 10% discount for the selected items is to add up all those discounts. what kind of formula should i use and I can keep it all on the same cell.

Thank you

[mikeTRON]

Can you post a sample workbook with the data and a proposed layout so we can help you?
Be sure to indicate a cell where you want a formula and what an example answer would be.


I think you can likely use a simple SUMIF formula to grab everything with a D then multiply by the discount at the end.