Make sure that you understand the difference between the following pairs of terms.
sheet vs page
opposite side vs reverse side
You wrote "opposite side of the sheet" instead of "reverse side of the sheet". They're asking for the page numbers on the reverse side.
If you need help visualizing what's happening with page numbers in this exercise, then get yourself a few sheets of paper and fold each of them in half, stack the folded sheets as though they were a newspaper, and then number the pages from front to back.
After you've numbered the pages, disassemble your "newspaper" and examine what's happening with the page numbers. You should see four page numbers per sheet of paper; two on one side, and two on the reverse side.
Look for a pattern!
Please come back here and post some specific questions or thoughts, if you require more guidance.
Cheers :cool: