Question

A man can complete a job in 12 days and his wife can complete the same job in 15 days. How long will they take to complete the job if they work together?

Answer 1

Answer:

20/3 days.................

Answer 2

Answer:

$If \: a \: man \: can \: complete \: a\: job \: in \\12 \: days$

$Then \: the \: man \: 1 \: day \: job = \frac{1}{12}$

$If \: his \: wife \: can \: complete \: a\: job \: in \\15 \: days$

$Then \: she \: finish \: 1 \: day \: job = \frac{1}{15}$

$(man + wife ) 's \: one \:day \:job \\= \frac{1}{12} + \frac{1}{15} \\= \frac{ 5+ 4}{60} \\= \frac{9}{60} \\= \frac{3}{20}$

$Together \: they \: finish \: the \: job \: in \\ \frac{20}{3} \: days$

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