Answer
(a) 118
(b) $C=30d+0.1m$
(c) 500
Work Step by Step
(a) The cost of renting the car is: $C=30d+0.1m$, where $d$ is the number of days rented and $m$ is the number of miles driven.
Since $d=3$ and $m=280$, we have:$C=30*3+0.1*280=90+28=118$
Thus the cost is \$118.
(b) As stated above: $C=30d+0.1m$
(c) We have: $d=3$ and $C=140$:
$140=30*3+0.1m$
Solving for m:
$m=(140-30*3)/0.1=(140-90)/0.1=50/0.1=500$
So the car was driven for 500 miles.
