X works alone for 2 hours to produce 6 machines, and Y works alone for 2 hours to produce 8 machines. In a task, at least one person is working, 44 machines are produced in 7 hours (that is, two people work together for a period of time, one person works alone for a period of time). If x and y cooperate to produce 44 machines with the shortest working time, how many hours do they work simultaneously?
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正确答案: D