Problem 16

Explanation

This problem involves inverse proportion. If the number of workers increases, the time required decreases, and vice versa.

Given:

• $15$ people can complete the work in $35$ days.
• The work is desired to be completed in $3$ weeks $= 3 \times 7 = 21$ days.

Let $P$ be the total number of workers needed to complete the work in $21$ days.

So, a total of $25$ workers are needed.

The question asks for the additional workers. The initial number of workers is $15$.

Thus, $10$ additional workers are needed.