A can do a piece of work n 7 days of 9 hours each and B alone can do it in 6 days of 7 hours each. How long will they take to do it working together 8 2/5 hours a day? Choose the most appropriate option.
A) 4 days  B) 3 days  C) 5 days  D) 6 days  E) 8 days
B   3 days   A can complete the work in   (7*9)= 
<gadget id="calculator">  (7*9)</gadget>
<output>63</output>
63 days   B can complete the work in   (6*7)= 
<gadget id="calculator">  (6*7)</gadget>
<output>42</output>
42 days   --&gt; A’s one hour’s work= 1/63 and B’s one hour work = 1/42.   (A+B)’s one hour work = 1/63+1/42 = 5/126   Therefore, Both can finish the work in 126/5 hours.   Number of days of 8 2/5 hours each = (126*5/(5*42))= 
<gadget id="calculator">(126*5/(5*42))</gadget>
<output>3</output>
3 days
<result>B</result>
A can do a piece of work n 7 days of 9 hours each and B alone can do it in 6 days of 7 hours each. How long will they take to do it working together 8 2/5 hours a day?