Okay, you need to dec 28 sts over 72. I think I'd do it as p2tog, p1, p2tog, p1 etc. Although it's worded oddly, that you're to begin the 2x2 rib, but you'll be decreasing in the rev St st...? Or do they mean to dec in the purl sts? In which case it would be k2, p2tog, k1, p2tog or something if you're supposed to be doing ribbing. Basically you're going to dec by about 1/3 so you should start out with the dec, work one st, dec, work a st, etc... ending with a dec.