Final answer:
The unit rate for purchasing tickets, when given a total cost of $420 for 15 tickets, is calculated by dividing the total cost by the number of tickets, resulting in $28.00 per ticket.
Step-by-step explanation:
To find the unit rate for purchasing tickets, we divide the total cost by the number of tickets. In this case, we have $420 for 15 tickets. Calculating the unit rate, we get:
Unit rate = Total cost / Number of tickets
= $420 / 15 tickets
= $28 per ticket
Therefore, the unit rate is $28.00 per ticket, which corresponds to option A.