At the gas station, Chrissy already has 4 gallons of gas, and she pumped gas at rate of 3/10 per second, so at s seconds she has:
![\text{gas}=4+(3)/(10)s](https://img.qammunity.org/2023/formulas/mathematics/college/onk60fbio3u7fbs50o77yfyhcvevhosii4.png)
In the equation above, the 4 is the initial amount of gas in the car (4 gallons) and the other term is the gallons pre second she pumped.