A is thrice as efficient as B and is, therefore, able to finish a piece of work 10 days earlier than B. In how many days A and B will finish it together? Pick one
A) 3 days	B) 2 days	C) 5 days	D) 6 days	E) 7 days
5 days   5 days   W5 days = 3:1   WT = 1:3   x 3x   1/x – 1/3x = 1/10   x = 20/3   3/20 + 1/20 = 1/5 =&gt; 5 days
<result>C</result>
A is thrice as efficient as B and is, therefore, able to finish a piece of work 10 days earlier than B. In how many days A and B will finish it together?