I want to create a custom calculation to determine the normalized concentration of a peak relative to the other peaks in the chromatogram. For example: The 4 peaks I have are methanol, ethanol, Isooctane, and Heptane and their respective concentrations. I need the equation to be: Normalized Ethanol Concentration = (ethanol concentration*100) / Sum of all peak concentrations). Then have that normalized ethanol concentration print out on the report. Any help with this would be greatly appreciated and save me a lot of time from manually calculating this in excel.