2. The amount of 4800 denars should be equally divided among several friends. If three of the friends refuse their share, then the remaining friends will receive 80 denars more each.

How many friends participated in the distribution of this amount?
Solution: Let $n$ be the number of friends, and $x$ the amount each of them will receive. We have:

$$
n \cdot x=4800 \ldots(1) \quad(n-3) \cdot(x+80)=4800
$$

From (1) and (2) we get:

$$
\begin{aligned}
& (n-3) \cdot(x+80)=n \cdot x \quad \text { or } \quad n \cdot x+80 n-32 x-240=n \cdot x . \\
& \text { or } \quad 80 n-32 x-240=0 \ldots \text { (3) }
\end{aligned}
$$

From (1) we have that $x=\frac{4800}{n}$, substituting in (3) we get:

$$
80 n-\frac{14400}{n}-240=0 ; \quad n^{2}-3 n-180=0 ; \quad n(n-3)=180, n=15
$$

Thus, 15 friends participated in the distribution.