Inc 1 st at each end of 5th and every 10th row?

What on earth does this mean? I’m telling you, for an “easy” pullover, this pattern has puzzled me quite a bit. Here’s the full pattern for the sleeves, which is where this line comes from:

SLEEVES

Using smaller needles, cast on 30 sts. Work in 2x2 rib for 1½", ending with a RS row.

Next Row Rib 6, M1, (rib, M1) 3 times, rib 6 – 34 sts. Change to larger needles and cont St st, inc 1 st at each end of 5th and every 10th row – 42 sts. Work even until Sleeve measures 11½ inches, ending with WS row. Bind off loosely.

Does “Inc 1 st at each end of 5th and every 10th row” mean I inc 1 stitch at each end of every 5 and every 10th row? So I would, for example work in St st for four rows, inc 1, knit to end, inc 1, cont in St st for 5 rows, and repeat? Or would I work in St st for four rows, inc 1, knit to end, inc 1. Cont in St st for 4 rows, inc 1, knit to end, inc 1. *Cont in St st for 9 rows, and inc st at each end, repeating from *?

None of the above. Increase on [B]the[/B] 5th row (after 4 rows of stockinette), then every 10th row. It doesn’t say every 5th [B]and[/B] 10th, so you only do the 5th row once.

Thanks! Now I can get this finished, hahaha