days taken for a piece of work

[rameshppc]

A,B & C together can finish a piece of work in 4 days. A alone can do in 12 days & B alone in 18 days. How many days will taken by C to do it alone?

Pls explain how do i workout this sum?

[nathi123]

Let C finish work in x days [tex]\Rightarrow for 1 day C finish[/tex] [tex]\frac{1}{x}[/tex]of work; A finish for 1 day [tex]\frac{1}{12}[/tex]; B- for 1 day finish [tex]\frac{1}{18}[/tex]
[tex]\Rightarrow \frac{4}{12} + \frac{4}{18}+\frac{4}{x} = 1 \Leftrightarrow 3x+2x+36=9x\Leftrightarrow x=9[/tex] days.

[rameshppc]

wow thanks a lot...
You are really great..