Answer:
![y=13\text{ miles per gallon}](https://tex.z-dn.net/?f=y%3D13%5Ctext%7B%20miles%20per%20gallon%7D)
Step-by-step explanation:
We have the two points: (0, 11) and (3, 50).
And we want to find the rate of change in y relative to x, where x is the gallons and y is the miles.
In simple terms, we want to find the slope between the two points.
So, let's use the slope formula:
![m=\frac{y_2-y_1}{x_2-x_1}](https://tex.z-dn.net/?f=m%3D%5Cfrac%7By_2-y_1%7D%7Bx_2-x_1%7D)
Let (0, 11) be (x₁, y₁) and let (3, 50) be (x₂, y₂). Substitute. Let's also put "miles" in the numerator with the Ys and "gallons" in the denominator with the Xs. This yields:
![y=\frac{50-11\text{ miles}}{3-0\text{ gallons}}](https://tex.z-dn.net/?f=y%3D%5Cfrac%7B50-11%5Ctext%7B%20miles%7D%7D%7B3-0%5Ctext%7B%20gallons%7D%7D)
Subtract and reduce:
![y=39\text{ miles}/3\text{ gallons}=13\text{ miles per gallon}](https://tex.z-dn.net/?f=y%3D39%5Ctext%7B%20miles%7D%2F3%5Ctext%7B%20gallons%7D%3D13%5Ctext%7B%20miles%20per%20gallon%7D)
And we're done!