Dell Inc. said Monday it would acquire EMC Corp. in a transaction valued at about $67 billion. EMC’s board has approved the merger. The deal includes new common equity from Michael S. Dell, MSD Partners, Silver Lake and Temasek, the issuance of tracking stock, as well as new debt financing and cash on hand. Mr. Dell and related stockholders will own about 70 percent of the company’s common equity. Michael Dell will lead the combined company as chairman and CEO while Joe Tucci will continue as chairman and CEO of EMC until the transaction closes.