A direct variation means that as one variable changes, another variable changes in the same direction as the first variable.
We can represent this relationship in the form:
[tex]\begin{gathered} p\propto q \\ \text{where p and q are the changing variables} \\ This\text{ relationship can be re-written as :} \\ p\text{ = k}\times q \\ \text{where k is the constant of variation} \end{gathered}[/tex]
Now, we can assign values to q and p from the coordinates (3, 18).
After doing this, we can calculate the value of k
if p = 18 and q = 3
We have:
[tex]\begin{gathered} 18\text{ = k}\times3 \\ \text{divide both sides by 3} \\ k=\frac{18}{3}=6 \end{gathered}[/tex]
Now that we have the constant of variation, we can calculate the value of n
[tex]\begin{gathered} n=2\times k \\ \text{but we know that k = 6} \\ n=2\times6=12 \end{gathered}[/tex]
Therefore n = 12