The initial value is $20 while the rate of change is $7.50 per hour
Here, we want to calculate the initial value and the rate of change
From the question, we have the rental fee as $20
What this mean is that before the truck starts to work, there is already a charge of $20 as the rental fee
Secondly, we have it that we want to calculate the rate of change
The rate of change here deals with the amount charged per hour
This is given as $7.50 per hour