Determing the stitch count

I would love to knit a chevron afghan but I have no idea how many stitches I would need to cast on since the pattern stitch I want to use does not give a stitch multiple count. This is the pattern I want to use:

Stitch pattern: 1 stitch at each edge in garter, which folded under very nicely, leaving a clean edge, then between these garter edge stitches, 3 repeats:

Row 1 (RS): K2tog, K5, YO, K1, YO, K5, Sl1, K1, psso

Row 2: Purl

Repeat these 2 rows for pattern.

Can someone determine what the multiple of the stitch is for a single repeat?

You need 15 stitches + 2 (1 border stitch at each end).
If I counted correctly.

Depending on your yarn, 32 stitches could make a scarf.
It also depends on how big you want the afghan to be.

You should to a swatch with a few repeats and from that determine the size you want the afghan to be and make an approximate how many repeats you need.

Oh, I just see, the pattern says “3 repeats”.