Interactive form

I need an application which I can implement on our web page. I have made a quick mock up. Please see attachment. Based upon the information the user fill in the application will estimate a yearly saving which then should be displayed where it stands “xxxx” The calculation is fairly simple. The field “supplier” will be a dropdown list and there will be four alternatives here. • If choose supplier 1 yearly savings is “a – discount x consumption” • If choose supplier 2 yearly savings is “b – discount x consumption” • If choose supplier 3 yearly savings is “c – discount x consumption” • If choose supplier 4 yearly savings is “d – discount x consumption” The values a, b, c and d will be given by me. If the discount the user fill in is bigger than a,b,c or d the message “We are sorry. We can’t help you with any savings” should display. Let me know if there are any uncertainties.