Four containers of flour are on the table

The first table contains 1/3 of a pound,the second contains 1/6 of a pound,the third contains 1/9 of a pound ,and the fourth contains 1/18 of a pound .if each container can hold one pound of flour.how many additional pounds of flour are required to fill all four containers?
a)2/9
b)2/3
c)11/9
d)25/9
e)10/3
can any one plz xpaln

all four containers can hold 4 pound of flour.
therefore

{ Total flour subtracted by flour present = flour required }
therefore, 4 - (flour already present) = flour required
=> 4/1-(1/3+1/6+1/9+1/18) = flour required
=> (72-6-3-2-1)/18 { Taking 18 as LCM } = flour required
=> 60/18 = flour required { Divisible by three }
=> 10/3 = flour required
so the answer is e) 10/3 = flour required