Adult vs Child Ticket Sales

A school is running a fundraising event and has two types of tickets: adult tickets and child tickets. Let the number of adult tickets sold be represented by a and the number of child tickets sold by c. The adult tickets cost $12 each, and the child tickets cost $8 each. If the total revenue from ticket sales is $960 and the number of tickets sold is 100, find the number of adult tickets sold.

We can set up the following equations based on the information provided:

1. $$ a + c = 100 $$

2. $$ 12a + 8c = 960 $$

Using these equations, determine how many adult tickets were sold.