a. To solve this question it is necessary to evaluate the function in x=5, it means replace x for 5 in the equation
[tex]\begin{gathered} C(x)=17.5x-10 \\ C(5)=17.5\cdot5-10 \\ C(5)=77.5 \end{gathered}[/tex]
It costs $77.5 to buy 5 tickets
b. This time, you have to replace C(x) for 130 in the equation and find x
[tex]\begin{gathered} C(x)=17.5x-10 \\ 130=17.5x-10 \\ 140=17.5x \\ \frac{140}{17.5}=x \\ x=8 \end{gathered}[/tex]
You can buy 8 tickets with $130
