Answer
$\$220$
Work Step by Step
From part (a), we have
Total cost = (Cost/hour) (Driven Hours)+ Annual Fee
This gives:
Total cost ; $C=8.50t+50$
Here, $t$ is in hours and $C$ is in dollars
Now, plugging in $t=20$, we get
$C=8.50(20)+50 =\$220$