We know that y varies directly with x, this means that:
[tex]y=kx[/tex]If x=8 and y=80, then:
[tex]\begin{gathered} 80=8k \\ k=\frac{80}{8} \\ k=10 \end{gathered}[/tex]Hence:
[tex]y=10x[/tex]Now, if y=120, we have:
[tex]\begin{gathered} 120=10x \\ x=\frac{120}{10} \\ x=12 \end{gathered}[/tex]Therefore, if y=120 than x=12.
