Create an online ROI Calculator for my website

I have a relatively simple ROI calculation on an Excel spread sheet that I would like to black box (so that the user can not see the underlying calculations, they can only see their assumptions and the end result). This ROI calculator then needs to be put up on my website with my website's colour scheme, fonts and style, for visitors to input their own assumptions and work out the ROI of my solution for their own organisation. Here is a copy & paste version of the spread sheet so that you can see what is required. I will provide the actual spreadsheet to the Freelancer upon appointment. ROI Calculation Improved Sales Productivity 1st Yr 2nd Yr 3rd Yr Annual Sales Target ($) $50,000,000 $55,000,000 $60,500,000 How many Salespeople ? (#) 50 50 50 Avg Sales Price per Solution ($) $20,000 $22,000 $24,200 Total Sale Closings per year (#) 2500 2500 2500 Avg. Sale Closing Rate 33.33% 33.33% 33.33% # of Sales Pursuits per year required (#) 7,500 7,500 7,500 Avg. "No Decision" or Lost Sales per year 5,000 5,000 5,000 5% Number of fewer poorly qualified Sales Pursuits per year 250 250 250 Resulting in Additional Closing per year (#) 83.3 83.3 83.3 Additional Sales Revenue per year ($) $1,666,675 $1,833,343 $2,016,677 Cost of Additional Sales (%) ($166,668) ($183,334) ($201,668) Added Margin per year ($) $1,500,008 $1,650,008 $1,815,009