13.064. The hay reserve is such that 96 kg can be issued daily for all the horses. In fact, the daily portion for each horse could be increased by 4 kg because two horses were sold. How many horses were there originally?
Solution.

Let there initially be $x$ horses. The daily portion for each horse was $\frac{96}{x}$ kg. Since two horses were sold to another collective farm, the number of horses became $x-2$, and the daily portion for each horse became $\frac{96}{x}+4$ kg. According to the condition, $\left(\frac{96}{x}+4\right)(x-2)=96$, from which $x=8$.

Answer: 8.