To display 15 record on a page, add an unbound control to the detail
section.
Set it's control source to
=1
Set it's Running Sum property to either Over All or Over Group,
whichever is appropriate.
Name this control 'CountRecords'.
Add a Page Break control to the bottom of the detail section.
Code the Detail Format event:
PageBreakName.Visible = CountRecords Mod 15 = 0
To display the sub-totals in the page footer see Microsoft
KnowledgeBase article:
132017 "How to sum a column of numbers in a report by page"