A, Band C can do a piece of work in 11 days, 20 days and 20 days respectively, working alone. How soon can the work be done if A is assisted by Band C on alternate days?	Choose the correct option:
A) 7 days	B) 8 days	C) 9 days	D) 10 days	E) 11 days
(7 days+B)'s 1 day's work = 1/11+1/20 = 31/220   (7 days+C)'s 1 day's work = 1/11+1/20 = 31/220   work done in 2 day's = 31/220+31/220= 31/110   31/110th work done in 2 days   work done= 110/31*2 = 7 days (approx)   7 daysNSWER:7 days
<result>A</result>
A, Band C can do a piece of work in 11 days, 20 days and 20 days respectively, working alone. How soon can the work be done if A is assisted by Band C on alternate days?