[tex]\begin{gathered} \text{ We had 15 dollars, and for n rides, the cost is 0.75n, and the entry is 7, thus the equation is} \\ 15-7-0.75n=8-0.75n \\ The\text{ expression to get the nuymber of tokens is} \\ 8-0.75n=0 \\ 8=0.75n \\ n=\frac{8}{0.75} \\ n=10.6667 \\ \text{You can purchase 10 tokens!} \end{gathered}[/tex]