Reading a pattern, 12 plus 1

I am trying to enlarge a pattern that I was working on. The orginal pattern called for 43, or it said muliple of 12 stitches plus 1…so how would I do the count for that…and of that orginal 43 sts, there was a border in the pattern of k3 on each end for a border. So not sure how I can enlarge this pattern keeping the k3 on each side of the work, and the pattern of 12 sts plus one? Any help would be greatly appreciated.

tia corinne

The actual sts that are repeated across the row are just the 12 sts, so add on more sts in increments of 12. The base is the 43, then with 12 that makes 55, another 12 is 67, etc.