[suzeeq]

To 'rib' 5 or 1 or whatever means to work that many sts in the rib pattern, not to make 5 ribs. You're making the med size so you'd start Row 4 with p1 then work 2 tog, and continue k1 p1 k1 p1 k1 p1, then work 2 tog. Do the 'rib 6, rib 2tog' 9 more times, and end with 6 st in the rib pattern and you should have a total of 82 sts when you finish the row.