For this case, the first thing we should do is define a variable.
We have then:
- t: number of minutes
- V: total volume
We write the linear equation that models the problem.
We know that:
- There are 10 gallons of water
- Each minute, 4 more gallons are added
Therefore, the equation modeling the problem is given by:

The formula defines a linear relationship.
Answer:

The formula defines a linear relationship.