A is twice efficient than B. A and B can both work together to complete a work in 7 days. Then find in how many days A alone can complete the work?	Choose the correct choice from the following answers:
A) 10.9	B) 10.5	C) 10.8	D) 10.1	E) 80.1
Ans: Let us assume A can do 2 units of work each day, then B can do only 1 unit a day. If both can complete the work in 7 days, total work done by these two togeter = (2 + 1 ) x 7 = 21 units   If these 21 units to be done by A alone, then he will take  21 / 2= 
<gadget id="calculator"> 21 / 2</gadget>
<output>21/2 = around 10.5</output>
10.5 days.   \Answer:10.5
<result>B</result>
A is twice efficient than B. A and B can both work together to complete a work in 7 days. Then find in how many days A alone can complete the work?