Video Tutorial

Chain 70
Row 1: chain 1, 25 single crochet, 20 half double crochet, 25 double crochet
Row 2: chain 3, 25 double crochet, 20 half double crochet, 25 single crochet
Repeat rows 1 and 2 to have 70cm on the part of single crochet
Make a button hole as we explain in the video
Continue making more rows to have 2 extra cm

Sew the button