Eastman Kodak Co.'s first-quarter net earnings fell 20 per cent despite a 5 per cent increase in sales.

The company said Sunday that its net earnings for the first quarter were $94.2 million (58 cents a share), down from the $118.1 million (73 cents) in net earnings for the same period in 1976.

Sales were $1.197 billion, up from $1.143 billion.

Kodak officials attributed the drop in earnings primarily to the rising costs of raw materials, higher wages, and exchange adjustments of foreign currency. The Kodak spokesmen also said that sales of its new instant photography line had not yet reached the point where it was making a profit. Last week, the company said it was laying off 150 workers at its instant-film plant.

The Great Atlantic & Pacific Tea Co. had lower earnings for the fourth quarter but the figure was sparkling for the whole year.

The company earned 7 cents a share for the quarter - which consisted of 13 weeks - against 11 cents in the year-earlier period of 14 weeks. For the year, earnings jumped to 96 cents a share against 17 cents the previous year.

The company said it had an extraordinary credit of $1 million in the quarter and $10 million for the year.The figures represented tax loss carryforward credits.

The supermarket chain's net profits for the quarter were $1.71 million on sales of $1.90 billion, against $2.73 million on sales of $1.86 billion a year earlier.

For the year, profits came to $23.7 million on sales of $7.23 billion compared with $4.31 million on sales of $6.53 billion last year.

Grand Union Co. yesterday reported decreased earnings and sales for its fourth quarter ended April 2, although results for the entire fiscal year topped those for the previous 12 months.

Fourth-quarter net income was $3.347 million (53 cents a share) compared with $5.122 million (83 cents) a year earlier. Sales fell from $395.9 million to $374.9 million.

Net income for the year was $17.6 million ($2.81) on sales of $1.623 billion compared with net income a year earlier of $11.7 million ($1.87) on sales of $1.611 billion.

American Motors Corp. yesterday said its profits in the first three months of 1977 more than doubled from the same 1976 period to $2.5 miilion, despite a worsening sales slump.

The smallest of the U.S. car producers said dollar sales in the January-March period declined by 10 per cent from a year ago to $534 million.

AMC's earnings in its latest quarter, equal to 8 cents a share, compared with a profit of $1.2 million, 2 cents a share, in the same 1976 period. Sales a year ago were $594 million.

For the first half of the fiscal year, AMC earned $3.7 million (12 dents a share), down 57.5 per cent from $8.7 million (29 cents) earned a year ago. Sales of $1.1 billion were off 8 per cent from $1.2 billion in fiscal 1976.

AMC has been in a severe auto slump for two years, and its U.S. car sales in the period - the second quarter of its fiscal year - plummeted 29 per cent from the already sluggish levels of the year before.

However, heavy losses in car operations were offset by strong performances by the firm's Jeep and bus-making subsidiaries, AMC officials said.

They added that the results for the quarter were stronger than anticipated in part because of a profit from the sale of its stamping plant in West Virginia to Volkswagen of America, and effective cost-cutting steps.

American Express Co. yesterday reported record first-quarter earnings of $50 million (69 cents a share), up almost 55 per cent over the $32.3 million (45 cents) earned a year ago. Revenue for the quarter was $764.5 million compared with $668.1 million for the first three months of 1976.

Addressing shareholders at the company's annual meeting, in New York, chairman Howard L. Clark also reported American Express will make a formal application for listing of the company's stocks on the New York Stock Exchange.

McDonnell Douglas Corp, yesterday reported that first-quarter profits were $28 million (73 cents a share), up from $25.3 million (67 cents) the previous year. However, sales were down at $759.3 million from $811.3 million for the comparable period in 1976.

The company attributed the earnings gain to sharply reduced borrowings and interest costs. The company reported a firm backing of orders of $2.93 billion compared with $2.7 billion for 1976, and a total backlog of $5.89 billion compared with $5.48 billion a year ago.

The Nestle Food Group yesterday announced 1976 net profits of $348.8 million, an increase of 9.1 per cent over 1975. Total sales in 1976 amounted to $7.64 billion for a rise of 4.2 per cent, it said.

Nestle said the board proposes a dividend this year of $28.80, an increase of $2.80 over the dividend last year.

Nestle president Arthur Fuerrer said that total sales would have increased by 16 per cent last year without currency exchange rate fluctuations.