When renting a car, the cost per mile is inversely

75

$0.2

Step-by-step explanation:

The standard equation of inverse variation is

y = k/x,

where k is the constant of variation.

We are given a point of this function.

When x = 300, y = 0.25

We can find k.

y = k/x

0.25 = k/300

k = 0.25 * 300

k = 75

Now we use the constant of variation to write the actual function.

y = 75/x

With the function, we can find the cost per mile for 375 miles.

y = 75/x; x = 375

y = 75/375

y = 0.2