The work involves 3 pieces of information:
- 8 men + 3 boys together finish work in 5 days
- 5 boys alone finish the same work in 15 days
- Need to find: 5 men alone will take how many days
5 boys finish the work in 15 days.
Total work =5×15=75 boy-days
One boy's one day work =751 of total work
8 men + 3 boys finish work in 5 days.
Work by 8 men in 5 days =8×5=40 man-days
Work by 3 boys in 5 days =3×5=15 boy-days
Total work =40 man-days +15 boy-days
Since total work =75 boy-days:
40 man-days +15 boy-days =75 boy-days
40 man-days =60 boy-days
1 man-day =1.5 boy-days
Total work =75 boy-days
Converting to man-days:
Total work =1.575=50 man-days
For 5 men:
Days needed =550=10 days
Therefore, 5 men complete the same piece of work in 10 days.