15 men can complete a work in 10 days while 20 boys can complete the same work in 15 days .How many days will 10 men and 10 boys together take to complete the same work	Choose one:
A) 9 days  B) 10 days  C) 11 days  D) 12 days  E) 13 days

Rationale: solution : work done by one man in one day = 1 / ( 15 * 10 ) work done by one boy in one day = 1 / ( 20 * 15 ) work done by 10 men and 10 boys in one day = 10 [ 1 / ( 15 * 10 ) + 1 / ( 20 * 15 ) ] days taken = 1 / work done by 10 men and 10 boys in one day answer b
Answer: B