Let x be the initial rental fee.
Since we know that the cost per hour is $12 and we also know that the rental was a five hour one we conclude that we spent $60.
Now, this amount plus the initial rental fee has to be equal to $74, that is:
[tex]\begin{gathered} x+60=74 \\ x=74-60 \\ x=14 \end{gathered}[/tex]Therefore, the initial fee (initial value) is $14. The rate of change is the cost per hour, that is $12.