Mom cooked homemade currant syrup and poured it into bottles. The bottles were of two types: small with a volume of $500 \mathrm{ml}$ and large with a volume of $750 \mathrm{ml}$. In the end, she had 12 empty small bottles left, and all other bottles were completely filled. Then Mom realized that she could have poured the syrup so that only large bottles would be left empty and all others would be completely filled.

How many empty bottles would she have in such a case?

(M. Petrová)

Hint. How much syrup did Mom lack to fill all the bottles?
Mom has 12 unfilled bottles, each with a volume of $500 \mathrm{ml}$. They could hold $6000 \mathrm{ml}$ of syrup $(12 \cdot 500=6000)$.

The same amount would fit into 8 large bottles $(6000: 750=8)$. If Mom were to pour the syrup the second way, she would be left with 8 empty large bottles.

Note. One large bottle has the same volume as one and a half small bottles, i.e., two large bottles have the same volume as three small ones. According to this guide, bottles can be appropriately exchanged to avoid dealing with large numbers: 12 small bottles have the same volume as 8 large ones.