Calculating Adult Ticket Sales

A theater is planning to sell tickets for a show. The price of an adult ticket is $12, and the price of a child ticket is $8. The total revenue from selling adult and child tickets is $680. Additionally, the theater sold twice as many adult tickets as child tickets. If we let a represent the number of adult tickets sold and c represent the number of child tickets sold, we can set up the following equations:

1. 12a + 8c = 680

2. a = 2c

Using this information, determine the number of adult tickets sold. Enter your answer in the grid below.