a can do a piece of work in 30 days while b..., Time & Work, General Mathematics

Question:A can do a piece of  work in 30 days while B alone can do it in 40 days.
In how many days can A and B working together do it ?

A 17`1/7` 
B 27`1/7` 
C 42`3/4` 
D 70

/47

+ AnswerA

+ Explanationsolution:
A's 1 day's work= `1/30` & B's 1 day's work = `1/40`.
`:.`(A+B)' s 1 day's work =`(1/30 + 1/40) = 7/120`.
`:.`Both together will finish the work in `120/7 =17 1/7` days.

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Question:A can do a piece of work in 30 days while B alone can do it in 40 days. In how many days can A and B working together do it ?

A 17`1/7`

B 27`1/7`

C 42`3/4`

D 70

A