Display Live Equations Results on Form while you input data on fields

Hi Guys,

I was wondering if there is a way to add to a form and equation field and see the result changing while I´m filling the form. For example, I have a field to set the starting date and then another one to insert the amount of day I have to delivery a service. The equation field take the starting date and adds the amount of days a I have. I would like to see the result as I´m adding those first field data to check the final result before submiting the form. 

Any ideas on how to acomplish that?