Answer:
![y=20x](https://img.qammunity.org/2020/formulas/mathematics/middle-school/xit3ikfmsei7uurgxu8mbj32g9zmjnvj7r.png)
Explanation:
By definition, a direct variation equation has the form shown below:
![y=kx](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ho37lptiefci31wskjnke7d88izbug72ti.png)
Where k is a constant, y is the dependent variable and x is the independent variable.
According to the problem, you know that your car gets 20 miles per gallon. The number of miles traveled varies directly with the number of gallons of gas the tank holds.
Then, you can write the following direct variation equation that represents the situation:
y: The number of miles traveled
x: the number of gallons of gas the tank holds.
k: 20 (Because your car gets 20 miles/gallon)
Then:
![y=20x](https://img.qammunity.org/2020/formulas/mathematics/middle-school/xit3ikfmsei7uurgxu8mbj32g9zmjnvj7r.png)