Question

Which is the function that gives the amount of money m that Margaret has as a function of the number of rides r that she takes ?

Answer 1

A ride costs $3, then
`r` number of rides costs
`3 * r = 3r`. As she takes more rides, her initial value of $35 will decrease by
`3r`. Re-writing this expression gives
`m = 35 - 3r`, where
`m` is the amount of money she has.

`m = 35 - 3r` can also be re-written as
`m = -3r + 35`