Average Rent PSF Formula?

Hi - I have an excel spreadsheet for an office building that I need to
calculate the average rent per square foot. In the spreadsheet I have 5
columns: 1 - Leased area (sf), 2 - term of the lease (mo), 3 - rental rate
for yr 1 ($), 4 - annual increase (%), and 5 - the months of free rent. I
need the formula to take this information and spit out the average rent per
square foot. Thanks for the help!

Here is what it looks like in excel:

Leased SF Term Rent Yr 1 Annual Increase Mo. Free Rent Avg. Rent
PSF
2,755 65 $20 3% 5
???