Marriott Corp.'s earnings last year were 20 percent higher than those for 1980. A headline in Wednesday's Business & Finance section gave an incorrect percentage for the increase

Expansion-minded Marriott Corp. reported yesterday that strong restaurant operations last year helped push profits up 20 percent on a 16 percent increase in sales.

The Bethesda-based hotel and food services firm said 1981 net income was $86.1 million ($3.20 a share) compared with $72 million ($2.60) the previous year, with sales rising from $1.72 billion to $2 billion.

In the fourth quarter alone, Marriott profits increased to $21.7 million (81 cents) compared with $16.9 million (64 cents) as sales rose to $620.7 million from $542.6 million.

Marriott, which recently announced agreements to acquire Host International and Gino's Inc., also revealed that Heublein Inc. has agreed in principle to acquire 80 Kentucky Fried Chicken restaurants now operated by Gino's. This is in line with Marriott's goal of converting 150 or more Gino's restaurants to Roy Rogers outlets and disposing of the remaining units, such as those with chicken specialties.

J. W. (Bill) Marriott Jr., president of the company founded by his father more than 50 years ago, noted that sales have doubled in the past five years with earnings per share up at a compound annual rate of 30 percent. In 1981, Marriott's return on equity (profits related to stockholders' investment) exceeded 23 percent "despite the recession, volatile financial markets and reduced air traffic," Marriott noted.

Looking ahead, Marriott said he does not expect national economic recovery to start until the second half of the year, "but the strengths demonstrated by the company in 1981 will help sustain it until the economy turns around." He said the takeovers of Host and Gino's should be completed later this month and in March, respectively.

Reviewing the company's major operations, Marriott said operating profits from hotels rose 12 percent in 1981 on a 25 percent increase in sales, with 23 new hotels and 10,250 rooms added in the recent 12 months. Contract food service operating profits rose 14 percent on a 13 percent rise in sales while restaurant operating profits spurted by 17 percent on a sales gain of 8 percent.

Marriott also tripled the size of its worldwide reservations center, based in Omaha, to handle a projected 2.3 million reservations a year by 1985.

Maryland Cup Corp., a manufacturer of paper and plastic food service products, reported record profits for the first quarter of its new fiscal year. Earnings for the three months ended Dec. 31 rose to $3.9 million (58 cents) from $3.7 million (55 cents) in the same period a year earlier, with sales up to $136 million from $131 million.