Info given
We have a total of people given (82). We also know that we have 54 children of under 12 years and under some children were under 3 years
We define x as the number of children under 3 years.
We want to find C for the total cost. We don't have the unitary prices but we can assume it as C1 (over 3 and lower than 12) and C2(adults) for children and adults.
Solution:
![C=C_1(54-x)+C_2(82-54)](https://img.qammunity.org/2023/formulas/mathematics/high-school/lae8nc4c4g2fwzfh4i9211lb5u7vzla8oh.png)
With C the total amount collected and C1 and C2 described above.