Buttonhole Method

Working on D. Bliss A Line Coat from The Big Easy Book. Buttonhole Row 1 reads: P to last 7 stitches, P2tog,y2rn, p2tog,k3 (wrong side). Row 2: K3,p1,p into front and back of y2rn, p to end. How do you p into front and back of y2rn? Have tried several times and can’t figure it out. Thank you.

The y2rn is a double yo which makes 2 loops on the needle. Then on the next row you purl into one loop of it, and ptbl on the 2nd loop. Or you can p the first and knit the 2nd, will look the same. The extra loop usually wants to fall off easily, so you can just let it and you’ll have one big loop that you can p and ptbl into.