To do this you can proceed as follows:
[tex]\frac{\text{Total amount earned for the team - y}}{\text{ The number of t-shirts - x}}=\text{ \$7.50}[/tex]Solving for you get
[tex]\begin{gathered} \frac{y}{x}=7.50 \\ \text{You multiply both sides of the quality by x} \\ \frac{y}{x}\cdot x=7.50x \\ y=7.50x \end{gathered}[/tex]Therefore, the correct answer is C) y=$7,50x.