Shaping raglan for the sleeve. at this point i have 67sts

pattern says to
cast of 3sts next 2 rows ( 61sts )
decrease 1sts each end 5 rows ( 49sts )
which i have done

Then this is where i am unsure. Next the pattern says.
Then on the 4th row, then on the foll 18 alt row
still 15sts
Does this mean decrease on 4th row and then on the 18 row. till i have 15sts
decrease 4th - 8th- 12th -16th - then 18th. till i get to the same amount of sts


Now dec on row 4 and then on rows 6,8,10,12,14,16, etc until there are 15 sts left. Alternate just means every other row.


Thank you for your reply. Just could not see want the pattern wanted e to do. Having knitting many sweater and cardigans my mind just went blank.