Subtracting page numbers

You cannot subtract from any reserved variable but you can move the reserved variable to one you create, subtract from it, and then add your variable instead of the system variable PagesInTitle or PagesInChapter.

I usually get around all this mess by setting up my course as follows:

Content chapter
Test chapter
Results of test chapter
Popup chapter

Then I use the PagesInChapter variable and it covers just the content.