In order to find the relationship between x and y, we can use a rule of three:
[tex]\begin{gathered} 5\text{ oz of tomato sauce}\to4\text{ oz of cheese} \\ x\text{ oz of tomato sauce}\to y\text{ oz of cheese} \\ \\ 5y=4x \\ y=\frac{4x}{5} \\ \frac{y}{x}=\frac{4}{5} \end{gathered}[/tex]