Help understanding a pattern

Well, I’m knitting a jumper (my first!) and am decreasing for the armholes.

The bit I am stuck on looks like this:
a) next row: k2, k2tog, k to last 4sts, sl 1, k1, psso, k2.
next row: p2, p2 tog tbl, p to last 4sts, p2tog, p2.

b) Working all armhole decreases as set by last 2 rows, dec 1 st at each end of next 3 rows, then on foll 4 alt rows.

Part b is where I get lost. I’ve got to reduce from 93 stitches to 75 but when I count up, it’s never 18 stitches that I am losing.

Any help would be much appreciated. It’s probably quite simple, but this is the most complex pattern I’ve ever followed, so I’m still getting used to it!

The following 4 every other rows is puzzling, but maybe you just do the decs on the RS rows only and purl on the WS rows. I do get just 16 sts decreased, is that what you get? I’d just do another dec on the purl row in there somewhere - maybe it was at typo and should read “dec 1 st at each end of the next 4 rows, then on the foll 4 alt rows”. Whatever gets you the correct number of stitches.

Thanks. I actually only got a 14 stitch decrease!

Working on the basis that this part of the pattern is asking me to create 9 rows, I got:

Row 1 - rs - lose 2 sts
2 - ws - -2
3 - rs - -2
4 - ws- -2
5 - rs - -2
6 - ws - -0
7 - rs - -2
8 - ws - -0
9 - rs - -2

But anyway, I think that I will take your advice to just make up the decreases on the purl, so thanks for the help.

EDIT: could it possibly mean 4 alternate rows and 4 other rows, so that you would make 8 new rows, reducing by 8 stitches instead of 4?

Oh wait, it does work out. You’re doing 5 rows at first, 2 sts on each row, that’s 10, then 4 ‘alt’ rows that’s 8 for 18 total. I forgot the purl row in the beginning setso was only counting 4 rows not 5. Your chart needs 2 more rows on it. The ‘foll alt rows 4 times’ means every other row for 4 dec rows, so you do 8 rows, not just 4.

I just worked out exactly the same thing at the same time! Thanks so much for your help - I would’ve been sitting here for hours otherwise!