Answer: Stacy's average speed is 3.55555555556 or approximate 3.56 miles per hour. Speed ≈ 3.56
Step-by-step explanation: You simply solve by taking the number of miles dividing it by the number of hours and you get 16 ÷ 4.5 which gets your answer to be approximately 3.56 miles per hour (mph). I hope this helped you! Let me know if you need me to explain more!