So our y value is the end cost, while our x value is the number of miles driven. Let's also add two variables, r and c. r stands for the rate, or the cost per mile, and c stands for the defined cost. So our function is y = rx + c. Remember that whenever we have a function, the y is replaced with f(x). No worries, they mean the same thing.
So let's add the values into each variable for both companies. Bert's company would have a function of f(x) = $3x + $1, and Madeline's company would have f(x) = $2x + $3. So let's say you drove 5 miles in a cab from both companies. x would become 5, so put that into both functions. 3 times 5 plus 1 would end up being $16, so Bert's company costs $16 for a 5 mile drive. 2 times 5 plus 3 would end up being $13, so Madeline's company costs $13 for a 5 mile drive.
