If 12 men or 20 women can do a piece of work in 54 days, then in how many days can 9 men and 21 women together do the work?
Choose the correct choice from the following answers
A) 10 days
B) 30 days
C) 20 days
D) 80 days
E) 40 days

Rationale: "b 30 days given that 12 m = 20 w = > 3 m = 5 w 9 men + 21 women = 15 women + 21 women = 36 women 20 women can do the work in 54 days . so , 36 women can do it in ( 20 * 54 ) / 36 = 30 days ."
Answer: B