To determine the unit rate, you need to find out how much it costs per person.
You can calculate the unit rate by dividing the total cost by the number of people:
\[ \text{Unit rate} = \frac{\text{Total cost}}{\text{Number of people}} = \frac{55}{20} \]
Now, let's perform the division:
\[ \frac{55}{20} = 2.75 \]
Thus, the unit rate is \(2.75\). This means it costs $2.75 per person.