If $15$ workers can build a wall in $48hours$, how many workers will be required to do the same work in $30hours$? (Answer in numbers)

Let the number of workers employed to build the wall in $30hours$ be $y$.

Obviously the more number of workers, the faster they will build the wall.
So, the number of hours and number of workers vary in inverse proportion.
So, $48\times 15=30\times y$
Therefore, y = $\frac{48\times 15}{30}=24$

i.e., to finish the work in $30hours$, $24$ workers are required.