## College Algebra 7th Edition

(a) 118 (b) $C=30d+0.1m$ (c) 500
(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.