It takes most oceans about 6 hours to go from high tide to low tide. Suppose that the water level decreases at a rate of 3 feet per hour during this time. How much does the water level change during this time?

From the level of high tide to low tide, it's 18 feet.

Step-by-step explanation:

To find the change in water level, we multiply the rate (3 ft / hr) by the time (6 hrs), obtaining 18 ft.

The water level changes by 18 ft.