Excel 2007 : Solve-Evaluate Formula for remaining principal amount

Hello, I'm taking a selftest on line and I can't solve the following:

Evaluate the formula for the remaining principal amount of the sixth month.

If someone knows how to solve this and needs the Excel real file letme know so that I can send it.


Thank You

had to scroll down than select cell F16 click on Formula ribbon -> Formula Auditng Group -> Evaluate Formula and executed everything that had to be executed.