Math
posted by Anonymous .
A car rental agency charges $120 per week plus $.12 per mile driven. How many miles did you drive if the total charge is $162?

Let's make a math sentence about how much the car company charges.
Flat Rate: $120 per week = $120 * W
Additional Fees: $0.12 per mile = $0.12 * M
Charge = Flat Rate + Additional Fees
Now let's plug in what we know:
$162 = $120(W) + $0.12(M)
Here's where I run into a problem. I don't know how many weeks we had this car. I know it must be below 1 week because 2 weeks would = $240 but what if the person had it for a 1/2 week or maybe 1 day. There are too many options. I'm assuming that this person had the car for 1 week:
$162 = $120(1) + $0.12(M)
$162 = $120 + $0.12(M)
$162  $120 = $0.12(M)
$42 = $0.12(M)
$42/$0.12 = M
350 = M
Therefore, we drove 350 miles.