The values of miles and hours are proportional. Then,
[tex]\frac{45}{4}=\frac{135}{n}[/tex]
To find n, multiply both sides by 4n.
[tex]\begin{gathered} \frac{45\cdot4n}{4}=\frac{135\cdot4n}{n} \\ 45n=540 \end{gathered}[/tex]
Now, divide both sides by 45:
[tex]\begin{gathered} \frac{45n}{45}=\frac{540}{45} \\ n=12 \end{gathered}[/tex]
Answer: n = 12.
