Acheetah can run 70 mph what is the speed in feet per hour

Construct the graph that models the given situation

Charlie is at an amusement park that has 18 different rides. each ride costs $1.75. the function c(r) = 1.75r represents the total amount of money that charlie will spend if he goes on r rides, but he never goes on the same one more than once. what domain and range are reasonable for the function?

Me because i don't understand how to do it.: )