20 17 nail factory recruitment master

If the specified time is X hours, it will take Master Zhang x-2 hours and x+4 hours to complete.

Enumerable equation: 3/(x-2)+x/(x+4) = 1,

Solution: x = 20 that is, the specified time is 20 hours.

Master Zhang needs 20-2 = 18 hours and 20+4 = 24 hours.

Li. Z completed this batch of binding tasks together, which took1(118+1/24) = 72/7 hours to complete.