Bernat Blue and White Blanket - issues with pattern instructions

I just started with a Bernat blanket knitting pattern. I am having difficulties understanding a couple of things:
Question: I am difficulty understanding what you are supposed to do with MK because, it seems, I am losing stiches by doing P2tog AND K2tog. I would assume you need to keep 181 sts but with MK I don't see how. Thanks for clarifying!
STITCH GLOSSARY MK = P2tog without slipping sts off needle, then K2tog over same sts.
INSTRUCTIONSWith MC and smaller needle, cast on 181 sts. Do not join.Working back and forth across needle, proceed as follows:Knit 5 rows (garter st), noting that first row is WS.
Change to larger needle and proceed in pat as follows:1st row: (RS). With A, knit.2nd row: P1. (MK) 90 times.3rd row: With MC, knit.4th row: (MK) 90 times. P1.These 4 rows form pat.Cont in pat until work from beg measures approx 42 ins [106.5 cm], ending on a 2nd row of pat.