Question

Three workers can do a job in $28$ $\mathrm{hours}$. How many more workers are needed to do this job in $12$ $\mathrm{hours}$?

Answer 1

Finding the workers needed to do the job in $12$ hours:

$3$ workers do the job in $28$ $\mathrm{hours}$.

$1$ worker will take $3\times 28=84$ $\mathrm{hours}$.

Let the number of workers needed to do the job in $12$ $\mathrm{hours}$ be $x$:

Then, $x=\frac{84}{12}=7$

So, $7$ workers will complete the job in $12$ $\mathrm{hours}$.

Therefore, $7-3=4$more workers are needed.

Hence, $4$ more workers are needed to do this job in $12$ $\mathrm{hours}$.