To find the unit rate, you need to divide the total number of deliveries by the total number of hours.
In this case, you have 45 deliveries in 3 hours.
So, the calculation would be:
\[ \text{Unit Rate} = \frac{\text{Total Deliveries}}{\text{Total Hours}} = \frac{45 \text{ deliveries}}{3 \text{ hours}} = 15 \text{ deliveries per hour} \]
Therefore, the unit rate is 15 deliveries per hour.