5 men and 12 boys finish a piece of work in 4 days, 7 men and 6 boys do it in 5 days. The ratio between the efficiencies of a man and boy is?	Choose the correct choice from the following answers:  A) 1:2  B) 2:1  C) 2:3  D) 6:5  E) 3:1
Explanation:   5Men + 12Boys ----- 4 days   7Men + 6Boys ------- 5 days   20Men + 48Boys = 35Men + 30Boys   18Boys = 15Men =&gt; 5Men = 6Boys   Men : Boys = 6:5   Answer: 6:5
<result>D</result>
5 men and 12 boys finish a piece of work in 4 days, 7 men and 6 boys do it in 5 days. The ratio between the efficiencies of a man and boy is?