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A can do a piece of work in 25 days and B can finish it in 20 days. They work together for 5 days, then A leaves. In how many days will B finish the work??

User Asibahi
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Think of it this way:

Both of them are doing 5 days of work. They both do some fraction of it.

5/25= A 1/5= 4/20

5/20= B 1/ 5/20

They do 9/20 of the work or 9 days of work.

20-9=11

It will take B 11 days to do the rest of the work.

I hope this helps!
~kaikers
User Nesha
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If A can do a piece of work in 25 days, then he can do
(1)/(25) of all work per day.

If B can finish work in 20 days, then he can do
(1)/(20) of all work per day.

Together per day they can do


(1)/(25)+(1)/(20)=(4+5)/(100)=(9)/(100)

of all work.

They work together for 5 days, then the work done after these 5 days is


5\cdot (9)/(100)=(9)/(20) of all work.

If then B finishes alone, it is left for him


1-(9)/(20)=(11)/(20) of all work.

Since B can do
(1)/(20) of all work per day, then
(11)/(20) of all work he can do in 11 days.

Answer: B will finish the work in 11 days.

User Bahbar
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