A can do a piece of work in 10 days and B alone can do it in 15 days. How much time will both take to finish the work ? Choose the correct choice from the following
A) 2 days  B) 7 days  C) 6 days  D) 9 days  E) 3 days
6 days   6 days   Time taken to finish the job = XY / (X + Y)   = 10 x 15 / (10 + 15)   = 150 / 25= 
<gadget id="calculator">150 / 25</gadget>
<output>6</output>
6 days
<result>C</result>
A can do a piece of work in 10 days and B alone can do it in 15 days. How much time will both take to finish the work ?