Need help reading a pattern...PLEASE!

Hello all. I haven’t been here in forever but I wanted some help on reading this particular pattern. Below is what I’m confused about.

Cast on 76 sts using US7 needles. Work in garter st for 4 rows, ending with a WS row. Change to a US8 needle. Beg with a K row, work in st st for 8 rows. Row 9 (RS): K3, M1, K to last 3 sts, M1, K3. Working all increases as set by last row, inc 1 st at each end of every foll 8th row until there are 84 sts. Work 13 rows, ending with a WS row.

The bolded sentences is what I dont understand. Does this mean that after every 8th row I will do the increase and once there are 84 sts, I will work 13 rows or do I just work 13 rows?

A little confused. Thanks in advance for all your help!!

Row 9 is your increase row, then every 8th row after row 9, you will increase as set until you have 84 sts. Then after that is all done you will work 13 rows stockinette stitch without increases. So in other words, work you increase row on row 9, 17, 25, 33, (this will be a total of 8 stitches increased, bringing you to 84 sts), then work 13 rows.