Question

if a can do work in7 days and b can do in 5 days how much time they both take to complete the work​

Answer 1

question if a can do work in7 days and b can do in 5 days how much time they both take to complete the work?

Formula:

$\frac{work \: }{time }$

'A' takes 7 days to finish 1 work .

& B takes 5 days to finish 1 work.

A's rate :

$\frac{1}{7} work \: per \: day$

B's rate :

$\frac{1}{5} work \: per \: day \:$

We need to find the rate of work done by both .

So, we basically needs to add the rate of work done by both individually.

$a \: and \: b \: rate \: = \frac{1}{7} work \: per \: day \: + \frac{1}{5} work \: per \: day \\ = \frac{1}{3} + \frac{1}{5} \\ = > \frac{5 + 7}{35} = \frac{12}{35}$

$\frac{12}{35} \: days \: both \: will \: take \: to \: complete \: work \:$

Thanks

Answer 2

a=7 days. 7days = 24 ×7=168hr

b= 5days. 5days =24×5 = 120hr

total time taken = 168 +120

= 288 hrs