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A can do a work in 15 days and B in 20 days


A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is :
A.
1
4
B.
1
10
C.
7
15
D.
8
15



Answer: Option D
Explanation:
A's 1 day's work =1;
15
B's 1 day's work =1;
20
(A + B)'s 1 day's work =(1+1)=7.
152060
(A + B)'s 4 day's work =(7x 4)=7.
6015
Therefore, Remaining work =(1 -7)=8.
1515








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