A ,B and C can do a piece of work in 15,12 and 20 days respectively they started the work together but c left after 2 days .in how many days will the remaining work be completed by a and b?
A, B, and C, can do a piece of work in 12, 15, and 20, days respectively. They started work together, but C left after 2 days. In how many days will the remaining work be completed by A and B?
If A can do this work in 12 days, he/she can do 1/12 of it in one day. If B can do this work in 15 days, he/she can do 1/15 of it in one day.
If C can do this work in 20 days, he/she can do 1/20 of it in one day.
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If they can do these fractions of this work on one day, adding these numbers up, we can see how much of this work is done in one day by the three people working at the same time: 1/12+1/15+1/20
=5/60+4/60+3/60=12/60
=1/5
So the three people can do 1/5of this work on one day. C left after two days, so before he left, 2/5of this work were done. A does 1/2 of it every day, and B does 1/15 of it every day, so together, they do 1/12+1/15
=5/60+4/60=9/60=3/20
it every day. Since 2/5 of this work were done when C left, when only A and B started working on the project, there were 3/5=12/20of this work left. If 3/20 of it is done every day, it takes four days to complete the rest of this work. The remaining work will be completed by A and B in 4 days.
If A can do this work in 12 days, he/she can do 1/12 of it in one day.
If B can do this work in 15 days, he/she can do 1/15 of it in one day.
If C can do this work in 20 days, he/she can do 1/20 of it in one day.
———————
If they can do these fractions of this work on one day, adding these numbers up, we can see how much of this work is done in one day by the three people working at the same time: 1/12+1/15+1/20
=5/60+4/60+3/60=12/60
=1/5
So the three people can do 1/5of this work on one day. C left after two days, so before he left, 2/5of this work were done. A does 1/2 of it every day, and B does 1/15 of it every day, so together, they do 1/12+1/15
=5/60+4/60=9/60=3/20
it every day. Since 2/5 of this work were done when C left, when only A and B started working on the project, there were 3/5=12/20of this work left. If 3/20 of it is done every day, it takes four days to complete the rest of this work. The remaining work will be completed by A and B in 4 days.
