Debt Settlement Calculator

I need a flash or javascript calculator for my website. I want visitors to be able to calculate what their monthly payments would be in my debt settlement program. The calculator should have a field to input total debt amount and a drop down field for the visitor to be able to select the number of months in the program (between 12 and 48). Once the information is inputted into the calculator it should calculate a monthly payment based on 55% of their total debt amount divided by the number of months plus $39.99. All I want the customer to see is the final calculation (not the breakdown of fees or percentages) All I want is the code to embed it in my website. Thank you very much.