Help understanding a pattern

Hi I’m Tracey I’m new.

I am a keen knitter and do some crocheting. However I’m struggling with a knitting pattern for short sleeved cardigan regarding decreasing for next and armhole at same time, I’m absolutely flummoxed I just can’t get to grips with what row I decrease neck then armhole, it’s just not working out, totally confused with 12 foll 3rd rows! Any help please.17314195757564498724518658996915|900x1200

Hello
If you all the “next row” row 1 then decrease neck edge on
Row 1 and 3 (3 is the following alternate row)
Then 12 foll 3rd rows are
Rows 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 6, 39

At the same time cast off armhole “next alt” will be
row 3
2 sts on Foll alt is
Row 5
Dec on 3 following alt rows are
Rows 7, 9, 11

These rows all happen at the same time. You might want to make a chart with row numbers and two headers of armhole edge and neck edge and tick which rows they happen on, then you can cross them off as you work them.

Hope this helps untangle the language.
What pattern is it?