The first bo's are for the underarms (appropriate place for bo, I always say!)
You only bind off at the beginning of rows so your yarn is in the right place when you finish. So on the next row bind of 3 st at the beginning, work to end.
Purl one row even
bo 3 st at beginning of k row, work to end
bo 2 at beginning " " "
bo2 at beginning
(bo1 at beginning. . ., next row p) 3X
When you get to 43 cm, you bind of the center 22 st. you will have to reattach the yarn for one side. Then at the neck edge, on each side of the center bo, you will bind off 2 st on every other row twice, as above.