P is three times as fast as Q and working together, they can complete a work in 16 days. In how many days can Q alone complete the work?
Choose the correct choice from the following choices:
A) 11 days
B) 16 days
C) 13 days
D) 64 days
E) 19 days
P = 3Q   P + Q = 3Q + Q = 4Q   These 4Q people can do the work in 16 days,   which means Q can alone do the work in 4*16= 
<gadget id="calculator">4*16</gadget>
<output>64</output>
64 days.   Answer : 64 days
<result>D</result>
P is three times as fast as Q and working together, they can complete a work in 16 days. In how many days can Q alone complete the work?