13.249. It was planned to divide the bonus equally among the most distinguished employees of the enterprise. However, it turned out that there were three more employees deserving the bonus than was initially expected. In this case, each would receive 400 rubles less. The union and administration found a way to increase the total bonus amount by 9000 rubles, as a result of which each awarded employee received 2500 rubles. How many people received the bonus?
Solution.

Let the number of people who were supposed to receive the award be $x$ and $y$ be the original total amount of the award.

According to the problem,

$$
\left\{\begin{array}{l}
(x+3)\left(\frac{y}{x}-400\right)=y \\
y+9000=2500(x+3)
\end{array}\right.
$$

from which $x=15$ people.

Therefore, the number of people who received the award is $x+3=15+3=18$ people.

Answer: 18.