I worked the Sl Rib Pat until my piece is 19'' from beg. Now I'm not sure how to proceed. The instructions say to work even until armholes measure 4 and then there is a Dec Row instruction below as well.
Row 2: P to first marker, work Row 2 of Sl Rib Pat to last marker, p to end. Work even in pat as established until piece measures 19(19-19½-19½-20-20)" from beg, end on WS. Mark beg and end of last row for beg of armholes. Work even until armholes measure 4(4-4½-4½-5-5½)", end on RS.
Dec Row (WS): P to first marker, drop marker, p to last marker, dec 13(11-13-11-13-11) sts as evenly spaced across as possible, drop marker, p to end - 72(82-90-100-108-118) sts. Work even in Garter St until armholes measure 8(8-8½-8½-9-9½)", end on WS. Mark center 28 sts on last row.