To complete a job, it takes 20 hours for Party A and Party B to cooperate, 28 hours for Party B and Party C, and 30 hours for Party C and Party D. So how small is the cooperation time between Party A

To complete a job, it takes 20 hours for Party A and Party B to cooperate, 28 hours for Party B and Party C, and 30 hours for Party C and Party D. So how small is the cooperation time between Party A and Party D? @ "Science and Family Education" answers for you.

Solution: The cooperation needs of four people1(1/20+1/30) =12 hours.

The cooperation needs of Party A and Party D1(112-1/28) = 21hour.

A: Jiading needs 2 1 hour.

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