In the pattern you are casting on a total of 220 stitches......
Then, the round reads...
Rnd1: [color=blue]p1[/color], [color=red]*(k1tbl) three times, p2, rep from *[/color] to last 4 sts, [color=blue]k3, p1 [/color]
The stitches in [color=blue]blue[/color] are 5 stitches that are not worked in the pattern.
The stitches in [color=red]red[/color] are the stitches worked in the pattern.
There are 5 stitches in blue so if you take the 220 cast on stitches and subtract 5 you are left with 215 stitches that are worked in the ribbing pattern.