Greyhound Corp., Phoenix, said Tuesday that net income for the first quarter rose to $32.7 million from $10.3 million. Per-share calculations for 1987 are based on 39.1 million average common and equivalent shares outstanding, down from 47 million shares in 1986, because of common share repurchase programs. Net income was reduced in 1987 by an extraordinary charge of $3 million, reflecting premiums paid on the early retirement of debt. In 1986, earnings included income of $2.2 million from a discontinued operation, representing equity in net income of ConAgra. The company's equity interest in ConAgra was sold in April, 1986.