To do a certain work, the ratio of the efficiencies of A and B is 7 : 5. Working together, they can complete the same work in 17 1 2 days. A alone will complete 60% of the same work in:

Using the combined work formula, the sum of their efficiency units is 12, and they complete the total work in 35/2 days, meaning the total work is 12 multiplied by 35/2, which equals 210 units. Since A has an efficiency of 7 units per day, 60 percent of the 210 units equals 126 units. Dividing 126 units by A's daily capacity of 7 units gives a completion time of 18 days.

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