Help needed with classic elite pattern stitch please!

This pattern stitch is for a scallop-edge border (having cast one and knitted one row first):
multiple of 12 + 3
Row 1 (RS) K1, ssk, *k9, sl2, k1, p2sso; rep from *, end k9, k2tog, k1.
Row 2: K1 *p1, k4 (k1, yo, k1) in next st, k4; rep from *, end p1, k1.

SSK is defined as: Sl 1st and 2nd sts one at a time as if to knit; then insert point of left-hand needle into fronts of these 2 sts and knit them tog from this position.

(1) p2sso: ie pass two slip stitches over. Does that mean off the needle as in cast off, or back onto the left hand needle. I’m thinking the latter.
(2) It appears that at the end of row one you have less stitches left than began with by two: one for the ssk and one for the k2tog at the end of the row.
(3) what does k4 (k1, yo, k1) in next stitch mean: do I simply knit 4, then knit one, than yarn over then knit one? I assume not, that the syntax means something but I don’t know what. Can I do 'k1, yo, k1 all to the same stitch? But in order to make the pattern add up to 12 stitches it seems like it is as I first thought: ie the brackets and ‘in the same stitch’ don’t mean anything…
(4) Suppose I have cast one 39 stitches: should I have 30 stitches at the end of row one? It looks like 37 to me. But does that mean I am supposed to make them up during row 2: I don’t see how…

You can see I haven’t been knitting for long and am confused.
The pattern is p. 130 of Knitting the New Classics which is a Classic Elite pattern book. Sorry if this is too wordy…

Ok–let’s get this sorted out–

Row 1-k1, ssk k9, sl2, k1, p2sso end k9, k2tog, k1

Row 2-k1p1, k4, (k1, yo, k1)in next st, k4, rep from p1, k1

You start with 99

So for the first row this is what you do–

k1, ssk, k9, sl2 k1, p2sso(for this you slip 2 st to the r needle, k1, the pass those 2 slipped stitches over the k1 st and off the needle) (repeat between * until you have 12 left, then k9, k2tog, k1

Looks like you have 85 at the end of this row

Second row-

k1, p1, k4 then you do the (k1, yo, k1) all in one stitch, k4 p1, k1
repeat part between * until you have 2 left

So for row 2, you start with 85 st, but with the increases by k1, yo, k1 in one stitch, you end up with 99 again.

I did the math, and it works out. I would say give it a try and see what happens.

If you do the dec and inc properly, it balances out.

Brilliant, Ingrid, thanks so much. It is 1am over here, so I’m for bed, but I’ve had a go and I think I more or less have it!

:thumbsup: Hang in there!