The cost, C, to get a ride in a taxi varies directly with the distance, D, traveled. When the distance is 6 miles the cost is $18. Find the cost when the distance is 30 miles.
Give one example of each of the following:
a. An even function: f(x) =
b. An odd function: f(x) =
c. A function that is neither even nor odd: f(x) =
