formulas in dropdown menu?

Hello everyone, so the experience I had here last time was amazing so why not return for this next question.

i have a spreadsheet that will be keeping track of my money in and out of clinic. I want to create a pop-up menu that will allow me to choose what percentage of pay is due to the Technician/Doctor

Ex: if I want them to get paid 40% i want G1 to look something like this sum(B1)x.40 or if i want to give them a Share Cost & Pay sum(B1)-(C1)-(F1)x.40

Is it possible to make formulas in a pop-up menu? Thanks for any help you guys can provide on this .....

Marshall