The equation to relate the total cost and the number of students would be:
[tex]C_{total}=C_{student}\cdot x[/tex]Where C is the cost, and x the number of students
If Mrs. Jameson paid a total of $202.50 for 9 students, we can find out how much does the visit costs for each student:
[tex]\begin{gathered} 202.50=C_{student}\cdot9 \\ C_{student}=\frac{202.50}{9}=22.50 \end{gathered}[/tex]So the equation for x number of students is:
[tex]C_{total}=22.50\cdot x[/tex]That's answer for part A
For part B we just have to put x = 9 +4 (four more students than before)
[tex]C_{total}=22.50\cdot13=292.5[/tex]The total cost for 13 students is $292.50
