I need a formula to create productivity report based on expended manhours against estimate

[Catalpa]

Hi
I need to create a productivity report based on actual expended man hours against the estimated hours. For instance: If the expended hours are equal to the estimated hours then a return of 1 is required. If the expended hours are 10% less than estimated then a return of 0.9 is returned. If the expended hours are 14% greater than estimated then a return of 1.14 is required and so on & so forth. What formula do I need to achieve this result?

Thanks in anticipation