30 boys are engaged to work for 15 days. After 5 days, 53 of the work is completed.
Total man-days used in 5 days:
30×5=150 man-days
Since 150 man-days complete 53 of the work, the total work requires:
53150=150×35
=250 man-days
Remaining work:
1−53=52
Remaining time:
15−5=10 days
Man-days needed for remaining work:
52×250=100 man-days
Number of boys needed:
10100=10 boys
Number of boys that can leave:
30−10=20 boys
Therefore, 20 boys may be allowed to go off.