Questions?

I've created an ROI calculator and one of the questions in my inputs asks the user to select values from a multi-select list. Each of the items on the list has a value assigned to it in the answer field. In my 'results' I am trying to set up a formula that considers all of the items that been selected from the multi-select list and uses their corresponding value as part of the formula. When I try to do this in the formula builder it doesn't seem to work