Answer:
y = 12,000x + 40,000
where y is the total miles driven, and x represents the number of years the owner drove the car
Explanation:
A linear equation is written in the form: y = mx + b, where m is the slope (rate of change of the equation) and b is the y-intercept, which is always a constant value (there is no variable attached to the y-intercept).
The constant value in this equation is 40,000, since that was the starting amount of miles the car had. This number can only increase, and it will increase by how much the owner drives the car.
The slope (rate of change, or how fast the graph increases or decreases) for this equation is 12,000, because that's how many miles the owner will drive it each year.
So each year, the change in the total miles is 12,000 miles per year. Since this rate is a constant value (it's always increasing at 12,000 miles) we use the variable 'x' to allow for increases depending on how many years it was driven.
After one year it increases 12,000 miles, after 2 years it increases 24,000 miles, after 3 years it increases 36000 miles, and so on...