None of those describe this function.
It's not a constant function, because it is not equal to a constant (something that isn't a variable)
It doesn't show direct variation, because it can't be represented in the form
y = kx.
It isn't an absolute value function because the absolute value isn't taken anywhere.
If it was an absolute value function it would look something like this:

It isn't a greatest integer function, because the greatest integer isn't taken anywhere.
If it was a greatest integer function it would look something like this:

Are you sure you typed that question right?
Answer:
37.6
Step-by-step explanation:
Where’s the picture of the question or the blank?
Answer: 7 gallons decrease per minute
Step-by-step explanation:
56 gallons / 8 minutes = 7 gallons per minute
to make sure do it backwards: 7 gallons x 8 minutes = 56 gallons :)