Question

A can lay railway track between two given stations in 16 days and B can do the same job in 12 days, with the help of C, they did the job in 4 days only, then C alone can do the job in ????

Answer 1

c can do this work in 8 days

Answer 2

A, B and C together do work in one day =

$\frac{1}{4}$

As one day work is

$\frac{1}{16}$

Bs one day work is

$\frac{1}{12}$

Then Cs one day work is

$\frac{1}{4} - ( \frac{1}{16} + \frac{1}{12})$

Find the LCM of 16,12,4 and by subtracting and adding

you will get

$\frac{5}{48}$

That's same as

$9 \frac{3}{5}$

Hope it helps :)