Mexico has signed a $183.7-million contract with...

Mexico has signed a $183.7-million contract with Hughes Communications International Inc. and Hughes Aircraft for two telecommunications satellites . . . Zenith Data Systems announced that it has signed an agreement with ComputerLand Corp. to offer ZDS’ laptop, desktop and file-server microcomputers to ComputerLand’s 393 locations nationwide . . . Mobil Corp. said it plans to boost capital spending on oil exploration to more than $5 billion this year from $4.4 billion in 1990 . . . U.S. District Judge Leonard B. Sand denied a request by Schneider SA of France to stop Square D Co. of Palatine, Ill., from postponing the annual meeting, originally scheduled for May 24. Sand said the company could delay its annual meeting until an antitrust challenge is resolved.