Need help finding linear function?

Question

I need help finding a real-life application of a linear function. State the application, give the equation of the linear function, and state what the x and y in the application represent. Choose at least two values of x to input into your function and find the corresponding y for each. State, in words, what each x and y means in terms of your real-life application.

Answer 1

total cost = (price per unit) x quantity

If gas is at $3.15/gallon and I buy 10 gallons, the cost will be $31.50. If I don't buy any gas, the cost will be $0.00