P can do a certain work in 20 days. Q is 60% more efficient than P. How many days does Q alone take to do the same job?
Choose one:  A) 18.5  B) 16.5  C) 12.5  D) 10.5  E) 8.5
Each day, P can do 1/20 of the work.   Each day, Q can do 1.6/20 of the work = 16/200 of the work   The time taken by B alone to complete the total work is   200/16= 
<gadget id="calculator">  200/16</gadget>
<output>25/2 = around 12.5</output>
12.5 days.   The answer is 12.5.
<result>C</result>
P can do a certain work in 20 days. Q is 60% more efficient than P. How many days does Q alone take to do the same job?