Manor Care Inc., the Silver Spring nursing home company that is trying to take over Hillhaven Corp., reported its operating income decline for the latest quarter, but net earnings increased five-fold because of the sale of two properties.

Manor Care's net jumped from $176,000 (10 cents a share) to $1,043,000 (62 cents per share) for the three months ended Feb. 28.

This year's earnings include a pretax gain from property sales of $1.3 million, compared with a $541,000 loss on property sales during the same period in 1977. Pre-tax operating income, without the extraordinary items, declined from $308,000 to $272,000. Revenues grew from $7.4 million to $9.1 million.

Manor Care this week won a favorable court ruling in its bid for Hillhaven Corp., another nursing home operator. A federal magistrate in Washington State refused to grant an injunction to block Manor Care's offer to purchase up to 1 million of Hillhaven at $13.50 a share.

Hillhaven is continuing to fight the offer, while Manor Care wages a separate legal battle in the state courts of Tennessee. In that case, Manor Care claims Hillhaven improperly issued a new series of convertible preferred stock of Hospital Affiliates International of Nashville, Tenn., in an attempt to block Manor Care's acquisition.

Pepcom Industries Inc., a Pepsi-Cola distributor, reported net income fell from $885,000 (34 cents per share) to $747,000 (29 cents per share) for the quarter ended March 31.

The company blamed increasing price competition for and production costs for the decline in earnings, which came as sales grew from $11.1 million to $12.2 million.

The operating income of Riviere Realty Trust of Washington more than doubled for the first three months of the year, from $48,000 (6 cents per share) to $98,000 (13 cents), and net income climbed to $133,000 including a property sale.

Joseph D. Riviere, chairman of the trustees, said the REI made a $34,000 gain on sale of its interest in Silver Hill Plaza Shopping Center. Earnings also increased because higher rents on the Coporate Square West office center and Chanticleer and Villa Paree apartments.

Fair Lanes Inc., the Baltimore bowling chain, reported earnings of $1.9 million (47 cents per share) for the third quarter ended March 31, up 9 percent from last year's $1.7 million (43 cents).

Revenues grew 10 percent, from $12.3 to $13.5 million for the company, which operates 69 bowling centers in nine states.