Question

A and B can do a work in 30 and 70 days respectively. If they work together,

how many days will they take to complete the work?​

Answer 1

Answer:

21 days to complete the total work

Step-by-step explanation:

A can do the  work in 30 days, B can do the work in 70 days

$\therefore in 1 day A completes \frac{1}{30} part of total work and in 1 day B completes \frac{1}{70} part of total work \\\therefore in 1 day total amount of work done by A and B together will be \\\\\frac{1}{30}+\frac{1}{70} = \frac{1}{10}(\frac{1}{3}+\frac{1}{7})=\frac{1}{10}\times\frac{10}{21}= \frac{1}{21}\\\\\therefore \frac{1}{21} part be completed by them in 1 day \\\\\therefore They take total 21 days to complete the total work$

Answer 2

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