movie theater charges $9 for adults and $7 for senior citizens. On a day when 325 people paid an admission, the total receipts were $2504. How many were seniors and how many were adults?

I will set it up.

Let a = adults

Let s = seniors

The first equation is a + s = 325.

The second equation is 9a + 7s = 2504.

Here is your system of equations:

{a + s = 325

{9a + 7s = 2504

Take it from here.

the answer is 99.