I am attempting to calculate the value between two points. I have an electric usage baseline and I want to setup a spreadsheet to calculate the values for the tier one and tier two rates. I have the values for each tier and I would like to be able to take the baseline, extrapolate the value that belongs in the tier one range and use the amount that is higher than tier one to extrapolate the value for tier two and so on. Can someone help me to figure out how to do this?