From the given table, we can note a linear behavior, then, we can find the rate by taking two rows of our table:

this rate must be preserved. It yields,

As we can note,when we add $2.75 plus $2.75 we obtain $5.50 and so on. Then, for 3 tickets, we have
$5.50 + $2.75 = $8.25. Then, the answer is $8.75