Question

$A$ and $B$ working together can mow a field in $56$ days and with the help of $C$ , they could have mowed it in $42$ days. How long would $C$ take by himself ?

• A. $168$ days
• B. $180$ days
• C. $151$ days
• D. $140$ days

Answer 1

The correct option is A $168$ days

A+B's 1 day work $=\frac{1}{56}$
A+B+C 's 1 day work $=\frac{1}{42}$
Thus, C's 1 day work $=\frac{1}{42}-\frac{1}{56}$
$=\frac{4-3}{168}=\frac{1}{168}$
Hence, C can complete work in $168$ days.