RJR Nabisco's earnings were up 19% to $320 million for the third quarter. The Atlanta company said sales were up 5% to $3.8 billion. In U.S. tobacco operations, higher prices, improved operating efficiencies and ongoing cost-containment programs contributed to higher sales and earnings for the quarter, the company said. In international tobacco, higher prices and the weaker dollar contributed to improved results. In the company's food business, particularly strong improvements were achieved by the U.S. biscuit and grocery divisions and Nabisco's international operations. Lower selling prices for bananas in the North American market affected Del Monte Tropical Fruit Co.'s performance.