Understanding 'alternating every third and fourth rows'

I am working on a vest and have come to the v-neck shaping part. I did the 1st row (RS) and then the 2nd row (WS). It now says: Repeat decs 16 times at neck edge, alternating every third and fourth rows. Dec will be on RS and WS rows. At same time, continue as before until piece measures 12 1/2 inches from beginning ending after a wrong side. Lion Brand pattern #20160 Double breasted vest. I am stuck!

Welcome to KnittingHelp!

If you call the row you’ve just worked row 2, then you would decrease 3 rows later (row 5) and then 4 rows after that (row 9), then in 3 rows (row 12) and then in 4 rows (row 16). Keep alternating the decrease row every 3rd and every 4th

A Big Thank You Salmonmac! Your explanation was clear and helped me put the whole thing together. Its amazing how a few words can throw you off, but seen in a different light, can unlock everything else. Thank you for taking the time to answer…the vest is going great :slight_smile: Also, I went to the video section you attached, and learnt a new stitch too! (Decreasing in a pearl row SSP)