64-Cent Sandwich on Saturday

 Arby’s Restaurant Group Inc. is celebrating its 47th anniversary Saturday with a promotion of its signature Classic Roast Beef sandwich that will cost only 64 cents, to match the year of the chain’s birth in 1964.  But the deal is not without a catch — Arby’s customers must purchase a 22-ounce $1.59 drink and show a required coupon that’s only accessible by “liking” the brand on i …