An aquarium is leaking water at the rate of 3 quarts per day. How many fluid ounces of water is this each hour?

The relevant information is that one quart is equal to 32 ounces.

This means that every day 3 quarts, or 3*32=96 ounces leak.

Per hour this is 96/24=4 (we have to divide the day into 24 parts, because there are 24 hours in a day).

This means that every hour 4 ounces of water leak.