Question

A and b can do a woekbin 72 days, b and c can do in 12 days and a and c can do a work in 90 days .If they work together how much work is finished by them in 3 days

Answer 1

A + B = 72days

B+C = 12days

A+C = 90days

then,

total unit of work = 360

so,

2A + 2B + 2C = 5 + 30 + 4

2(A+B+C ) = 39

A + B + C = 39/2 unit in 1 day

so,

39/2 unit = 1day

39/2*3 = 1 day

117/2 = 3days

58 fraction 1/2 = 3 days

so,.

the answer is 58 fraction 1/2

Answer 2

Hope you like my process

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Given

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• A and B can do work in 72 days

• B and C can do work in 12 days

• A and C can do work in 90 days.

NOW

In 1 day ,

A and B can do 1/72 part of work

B and C can do 1/12 part of work.

A and C can do 1/90 part of work.

Adding them

=> (A+B)+(B+C)+(C+A)=

$\it \frac{1}{72} + \frac{1}{12} + \frac{1}{90}$

So in 2 days, they together can do.

=> 2(A+B+C) =

$\it \: = \frac{5 + 30 + 4}{360} = \frac{39}{360} = \frac{13}{120}$

In 1 day they Together can do ,

=> (A+B+C) =

$\it \: = \frac{13}{120} \times \frac{1}{2} = \frac{13}{240}$

Thus in 3 days ,they together can do ,

=> 3(A+B+C) =

$= \it \: \frac{13}{240} \times 3 = \underline{\blue{ \: \frac{13}{80} \: \: }part \: \: of \: \: work. }$

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Thus in 3 days ,

13/80 = 0.1625 part of work is finished by them together.

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Hope this is your required answer.

proud to help you.