Explanation:

- Given situation: 4 men take 5 days working 9 hours a day to complete the task.

- Total hours of work needed: 4 men × 5 days × 9 hours = 180 man-hours.

- Revised situation with 10 men and 3 days:

- Let's see how many hours per day the 10 men need to work.

- Total man-hours they need to complete the work: 180 man-hours.

- Formula to find new hours per day:

- Set it up as: 10 men × 3 days × hours per day = 180 man-hours.

- Simplify to: 30 × hours per day = 180.

- Solve for hours per day: hours = 180/30 = 6.

- Conclusion: 10 men can complete the job by working 6 hours each day for 3 days.

- Highlighted Answer: Option:3 — 6.

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