At most, Alana can spend $40 on carnival tickets. Ride tickets cost $4 each, and food tickets cost $2 each. Alana buys at least 16 tickets. The system of inequalities represents the number of ride tickets, r, and the number of food tickets, f, she buys. r + f ? 16 4r + 2f ? 40 What is the maximum number of ride tickets she can buy? 4 6 10 12