From the given table, we can note a linear behavior, then, we can find the rate by taking two rows of our table:
[tex]\text{rate}=\frac{11.00-5.5}{4-2}[/tex]this rate must be preserved. It yields,
[tex]\text{rate}=\frac{5.5}{2}=2.75[/tex]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