Answer:
4x + 4y ≤ 80
6x + 8y ≤ 100
Step-by-step explanation:
Let's define x as the number of children and y as the number of adults.
For Matinee tickets, they spend $4 per child and $4 per adult, so if the total is no more than 80, we get:
4x + 4y ≤ 80
In the same way, they spend $6 per child and $8 per adult on the evening tickets, so
6x + 8y ≤ 100
Therefore, the system is
4x + 4y ≤ 80
6x + 8y ≤ 100