SOLUTION: A can do work in 12 Days,b in 6 days and c in 3 days.A and B start working together and after day,C jons them.The total numbers of days required to complete the work is ans:

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Question 780223: A can do work in 12 Days,b in 6 days and c in 3 days.A and B start working together and after day,C jons them.The total numbers of days required to complete the work is

ans:
a)16/7 b) 9/7 c)8/7 d)15/7
Found 2 solutions by josmiceli, lwsshak3:
Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website!
What fraction of the job do A and B get done
working together?
Add their rates of working to get their rate
working together
A's rate: ( 1 job ) / ( 12 days )
B's rate: ( 1 job ) / ( 6 days )
C's rate: ( 1 job ) / ( 3 days )
Let = fraction of the job they do in 1 day
I can say:

-------------------
They complete of the job, so there is
left to do
Now with all 3 working, let = days
to complete the job

Multiply both sides by

1 day has already been spent, so the total days worked is

(a) 16/7 answer
-------------
check:

OK

Answer by lwsshak3(11628) (Show Source):
You can put this solution on YOUR website!
A can do work in 12 Days,b in 6 days and c in 3 days.A and B start working together and after day,C jons them.The total numbers of days required to complete the work is
***
let x=number of days required to complete the work
A's work rate=1/12
B's work rate=1/6
C's work rate=1/3

LCD:12
x+2x+4x-4=12
7x=16
x=16/7
ans: a)