3 in 1 st from a 1950's sweater pattern

Just need some visual guidance.
Help me anyone. This is a stitch in a sweater pattern, that just not look right after I do it. It reminds me of a popcorn st. If I could see it worked, maybe my brain would catch on. Oh I’m a left-hand knitter; But I have tried it right-handed. not working.(Aran pattern)
work a “3-in-1” (rs row)
st as follows: P 3 tog. but do not drop
sts from left needle, k same 3 sts tog’
inserting needle through front of sts,
do not drop sts from left needle, p same
3 sts tog. and drop from left needle;

Hi and welcome!
It’s like a pfb only it’s a purl front, back and then front again [I]and [/I]you’re working 3 sts together rather than working into a single stitch.

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