A, Band C can do a piece of work in 11 days, 20 days and 55 days respectively, working alone. How soon can the work be done if A is assisted by Band C on alternate days?  Pick:
A) 7 days B) 8 days C) 9 days D) 10 days E) 11 days
(A+8 days)'s 1 day's work = 1/11+1/20 = 31/220   (A+C)'s 1 day's work = 1/11+1/55 = 6/55   work done in 2 day's = 31/220+6/55 = 55/220 = 1/4   1/4th work done in 2 days   work done= 4*2= 
<gadget id="calculator">4*2</gadget>
<output>8</output>
8 days   ANSWER:8 days
<result>B</result>
A, Band C can do a piece of work in 11 days, 20 days and 55 days respectively, working alone. How soon can the work be done if A is assisted by Band C on alternate days?