Not sure, but the help file says this:
=IF(A2<=100,"Within budget","Over budget")
If the number above is less than or equal to 100, then the formula displays "Within budget". Otherwise, the function displays "Over budget" (Within budget)
So, you'd replace the "Within budget" part of that with the Hide commands, whatever they are.
I know you can access Hide from Format>Row>Hide but I'm a bit of a n00b when it comes to Office.