Hi,

I think you should try using the rounddown function. To find out the number of weeks try the formula.
=ROUNDDOWN(C7/5,0)

Where you replace C7 with the cell outputting the number of days. This will give you the number of weeks. The number of days can then be found from the formula:

=C7-D7*5

Where D7 is the cell containing the above formula.

Hope that helps.