Sounds like it's time for a visit to Aunt Dot's Fudge Pot.
Since they are so thoughtful as to give you the number of stitches you start with - 102 - and the number of stitches they want you to wind up with - 92 - then you'd need to subtract one from the other, giving you 10 stitches you need to cast off.
Let's take 10 and divide it by 2... gives you 5 stitches for each side to bind off, if you're to keep your work even.
So. There you go. The Fudge Pot says, for your 5 rows, bind off [or cast off] ONE stitch EACH side - a total of 2 stitches - for each of your 5 rows.
Then work 50 rows over your 92 remaining stitches.
Does that sound right? Would it fit in with the end result of what you are making? If not- then back to the Fudge Pot for another try.
Hope this helps,