I did something in excel. What i did in excel: I sorted both sales data and rental data by the 28 locations and calculated average prices for each area both in terms of rent and sales price. Then i divided average sales price / average rental price area. By doing that i got a form of measure of ROI (how many months of rent do you need to cover the purchasing price). the lower the number, the better. Can someone help me how to do that in RapidMiner because it supposed to be done in RapidMiner not Exel?