To find the total change in the amount of water in the tank after 6 days, we need to calculate the change per day and then multiply it by the number of days.
Given that the tank decreases by 10 gallons every 3 hours, we need to convert this rate to a daily rate. There are 24 hours in a day, so we can calculate the hourly change:
10 gallons / 3 hours = 3.33... gallons per hour (rounded to two decimal places)
Now, to find the daily change, we multiply the hourly change by the number of hours in a day:
3.33 gallons per hour * 24 hours = 79.92... gallons per day (rounded to two decimal places)
Since the change is a decrease, the total change in the amount of water in the tank after 6 days will be:
79.92 gallons per day * 6 days = 479.52 gallons (rounded to two decimal places)
As the tank decreases in volume, the change is negative. Therefore, the correct answer is "negative 480 gallons" or "-480 gallons".