Answer:
7.5 inches per hour
Explanation:
Given that:
Morning low tide at beach = 12 inches
Afternoon tide after 6 hours = 57 inches
Average number of inches tide changed per hour :
(Afternoon tide - morning tide) / number of hours
(57 inches - 12 inches) / 6 hours
45 inches / 6 hours
= 7.5 inches per hour