Problem 5. If Mare buys 20 eggs from the market, 30 denars will remain from the amount she brought, and to buy 30 eggs, 20 denars are missing. How many denars did Mare bring to the market?
Solution. First method. The difference in eggs is 10, and they would cost $30+20=50$ denars. This means one egg cost 5 denars. So, the amount of money Mare brought to the market is $20 \cdot 5+30=130$ denars.

Second method. If one egg cost $x$ denars, then we have:

$$
\begin{aligned}
& 20 x+30=30 x-20 \\
& 10 x=50 \\
& x=5
\end{aligned}
$$

This means one egg cost 5 denars. Finally, the amount of money Mare brought to the market is $20 \cdot 5+30=130$ denars.

## V section