Answer: 5 hours
Explanation:
Carl paid $58 dollars in total and this included the fixed dollar fee and the variable amount of $9.
To find the number of hours, first deduct the fixed component:
= 58 - 13
= $45
$45 was spent as a result of hourly fee. The number of hours is therefore:
= Total hourly cost/ Cost per hour
= 45 / 9
= 5 hours