I am a beginning knitter and am knitting a pair of slippers. The directions are: row 1 - knit 7, purl 1, knit 29, purl 1

row 2: knit 17, purl 1, knit 9, purl 1, knit 17.

After I have 17 ridges, I am to cast off 7 stitches for 2 rows and continue pattern for 10 ridges. My question: What pattern would I be following, since I would have less stitches after casting off the 7 stitches. Also, does that mean to cast off 7 stitches in one row and 7 stitches in the next?

The site where I found the directions is:

http://knitting.about.com/library/blslippers.htm