Cindy is selling circus tickets. On the first day she sells 4 adult tickets and 9 children's tickets for a total of $108. On the second day she sells 5 adult tickets and 6 children's tickets for a total of $103.50. Determine the cost of an adult's ticket and a child's ticket. Use a to represent the cost of an adult ticket. Use c to represent the cost of a child's ticket. Write a equation to represent the sales from day 1. Write an equation to represent the sales from day 2. Use the elimination method to solve the system of equations.