Question

A rental car cost $25 plus a fixed charge per mile driven. The total charge for 210 miles of use was $67. Write an equation for the cost, C (in dollars), in terms of the miles driven, x.

Answer 1

To start, we know the basic equation from what us given:


`c = 25 + mx`
And we want to find m. Fortunately, we have some numbers to plug in to find m. We can make an equation like this

`67 = (210)m + 25`
by taking the amount charged and the amount of miles driven to get that charge given in the original problem.

Now we solve.

`67 - 25 = 210m + 25 - 25 \\ 42 = 210m \\ (42)/(210) = (210)/(210) m \\ (1)/(5) = m`
Now we can put that in our equation to finish it.

`c = (1)/(5) x + 25`
And that is the final equation