One selection sets two values for two different calculations

I have a dropdown called “Term” which sets the number of months a person wants to rent a product. I have two other calculations that need to be based on this selection: 1) the contract total which takes the value of the Term field options selected (12 months = 1.4, 24 months = 1.6, 36 months = 1.8 and 48 months = 2) and multiplies that by the retail price for a total contract price including interest. I then need that total contract price divided by the number of months selected for the monthly payment. Essentially, I need that one selection in the Term dropdown to supply two values to the rest of the form (ie; 24 AND 1.6 for the 24 month selection). How can I accomplish this?

Example:
Retail price = 5000
Term = 24 months (interest rate of 60%)
Total contract price = 8000
Monthly payment: 8000/24 = 333.33