Hi there - My name is Paris.
I've read your brief and can see that you'd like to have a formula. I have 7 years’ experience designing and developing Excel spreadsheets. I am highly qualified for this project and would love to speak with you further about taking this project on. If you'd like to view my previous work, as well as feedback, take a look at my Freelancer Portfolio (https://www.freelancer.com/u/paris2785.html).