A, B and C can finish a piece of work in 20,30 and 40  days respectively. They started the work together and...

A, B and C can finish a piece of work in 20,30 and 40 

days respectively. They started the work together and

 A leaves the work after 5 days. C leaves 10 days before 

completion of the work. In how many days would whole

 work have been finished?

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pramodpandey's profile pic

Posted on

Let when all they work together can finsh work in x days.

A can finish work in 1 day =(1/20) work

so in 5 days he will finish = (5/20) work

B can  finsh wiork in 1 day= 1/30 work

so he can finsh work in x days= (x/30) work

C can finish work in 1 day =(1/40) work

so in (x-10) days he can finish= (x-10)/40 work

Thus

(5/20)+(x-10)/40+x/30=1

(6.5+3(x-10)+4x)/120=1

30+3x-30+4x=120

7x=120

x=120/7 days.

 

 

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