A can do a work in 20 days. B is 30% more efficient than A. How many days does B alone take to do the same job? Choose the correct answer.
A) 121/23	B) 129/12	C) 198/13	D) 200/13	E) 199/18
Ratio of times taken by A and B = 130:100 = 13:10   suppose B alone to take x days to do the work   then, 13:10::20:x   13x= 10*20= 
<gadget id="calculator">10*20</gadget>
<output>200</output>
200/13 days   correct option is 200/13
<result>D</result>
A can do a work in 20 days. B is 30% more efficient than A. How many days does B alone take to do the same job?