A man can do a piece of work in 5 days. But with the help of his son, he can do it in 3 days. In what time can the son do it alone?
সমাধান
সঠিক উত্তর: Option C
A man can do a piece of work in 1 days=1/5 part
Both can do a piece of work in 1 days=1/3part
son do it alone=(1/3-1/5) part
=2/15 part
2/15 part done it in 1 days
1 part done in= 15/2 days=7.5 days
