To calculate the unit cost, you need to divide the total cost by the total time (in hours).
In this case, the total cost is 8 dollars, and the total time is 2.5 hours:
\[ \text{Unit Cost} = \frac{\text{Total Cost}}{\text{Total Time}} = \frac{8 \text{ dollars}}{2.5 \text{ hours}} = 3.2 \text{ dollars per hour} \]
So, the unit cost is $3.20 per hour.