Given that y and x vary directly, we have to use the following expression.
[tex]y=kx[/tex]Where k is the constant of proportionality between the variable.
Let's replace y = 75 and x = 1/5 to find k.
[tex]\begin{gathered} 75=k\cdot\frac{1}{2} \\ k=150 \end{gathered}[/tex]Then, we use k and x = 2 1/4 to find y.
[tex]\begin{gathered} y=kx \\ y=150\cdot2\frac{1}{4}=150\cdot\frac{9}{4} \\ y=337\frac{1}{2} \end{gathered}[/tex]