If A is thrice as fast as B and together can do a work in 15 days. In how many days A alone can do the work? Pick:
A) 36	B) 20	C) 28	D) 54	E) 45
A’s one day’s work= 1/X   20’s one day’s work= 1/3x   A + 20’s one day’s work= 1/x + 1/3x = 1/15   = 3+1/3x = 4/3x = 1/15   x = 15*4/3= 
<gadget id="calculator">15*4/3</gadget>
<output>20</output>
20   ANSWER:20
<result>B</result>
If A is thrice as fast as B and together can do a work in 15 days. In how many days A alone can do the work?