Question on armhole shaping - another added

I’m working on my first garment - a tank top. I’ve come to a part of the armhole shaping that I don’t understand.

[i]Last 2 rows form slip st edging and set armhole decreases.

Keeping sts correct as set, dec 1 st at each end of next and foll 3 alt rows.[/i]

What does the part in bold mean?

Any pattern that you’ve been following until now, just keep following. If it is stockinette, just do that, if it’s ribbing, that, etc.

That’s what I thought it might mean. But now I have another question.

The rows they are saying to continue go like this…

[i]P tog first st and the loop, P1, P2tog tbl, P to last 4 sts, P2 tog, P1, pick up loop lying between needles and place loop on right needle. (this loop does not count as a st), sl last st purlwise.

K tog tbl first st and the loop, K1, K2tog, K to last 4 sts, K2tog tbl, K1, pick up loop lying between needles and place loop on right needle. (this loop does not count as a st), sl last st knitwise[/i]

My next question is then, where do I decrease at each end of the row. The slip stitch is forming the edge. Do I need to add a decrease, or are the P and K togethers doing that? Help!

You are decreasing every time you k or p two together.

I think that the first directions telling you to decrease tell you when and the second set tell you how. Does that make sense?

Ingrid, you’re so sweet to help me, but I’m still confused. :?
I actually posted the 1st part of the pattern after the 2nd part. So it actually reads:

[i]P tog first st and the loop, P1, P2tog tbl, P to last 4 sts, P2 tog, P1, pick up loop lying between needles and place loop on right needle. (this loop does not count as a st), sl last st purlwise.

K tog tbl first st and the loop, K1, K2tog, K to last 4 sts, K2tog tbl, K1, pick up loop lying between needles and place loop on right needle. (this loop does not count as a st), sl last st knitwise

Last 2 rows form slip st edging and set armhole decreases.

Keeping sts correct as set, dec 1 st at each end of next and foll 3 alt rows. [/i]

If I just keep doing these 2 rows, how do I only decrease on every 3 alt row? Do I need to decrease and extra stitch ( by k2 tog or somethig?) Am I just making this harder than it is and just follow the rows as written? Hope it turns out right?

My impression when I read it this way, and I’m not 100% sure without seeing the shirt, is that you do these two decrease rows and then continue as you had been before that while you decrease at the edge every other row three times, by knitting two together.

This is what makes the most sense to me.