Help with knitting instructions - arms

Hi. I’m knitting a cardigan for my daughter and have got through the body without too many issues but I don’t understand the pattern instructions for the arms. The pattern is defined as 8 rows and you are instructed to inc 1 st at each end of row 5. At the end of the instructions as to the 8 row pattern, I have 43 stitches (after completing the first pattern). The instructions then state:
"Cont in patt working inc sts into patt. Inc 1 st at each end of foll 7th rows, then in foll 10th rows until there are 57 stitches."
What am I meant to do? I assume I inc 1 st at each end of the 5th row of each pattern but don’t quite understand the part re 7th and 10th rows. Can anyone help?

Welcome to the forum!
If you increase at each end of row 5, then the 7th row would be row 12 and the following 10th rows are rows 22,32,43,52 and 62 (14sts increased).
Which pattern are you following?

I am slightly confused it seems that you are following a repetitive pattern that is 8 rows long does this mean that your increases are repetitive also? What I am trying to understand is are you increasing on the 7th and then the 10th row and then just on the 10th row going forward or are you increasing on the 7th and 10th rows going forward, this would definitely make a difference as to which row an increase would occur. If it is just with the 10th row going forward then I would have to agree with Mod Squad otherwise the rows would be 22, 29, 39, 46 and 56 as you can see you would be alternating between the 7th and 10th row. Hope I did not confuse you.

Hi Mod Squad and Trisha
Thank you so much for taking the time to respond. It is a Heirloom pattern - generally it has been pretty simple with an easy design but this bit has really confused me. I’ll let you know how it goes.
Cheers, Lucy