When visiting friends in a state that has no sales tax, two families went to a fast-food restaurant for lunch. The Browns bought 4 cheeseburgers and 3 medium fries for $16,53. The
Greens bought 5 cheeseburgers and 4 medium fries for $21.11,
Using c for the cost of a cheeseburger and f for the cost of medium fries, write a system of
equations that models this situation,