How can I re-write an equation (or system of equations) in parametric form?

Question

For the equation $y = 3x$ I need to re-write $x$ and $y$ in terms of a variable $t$. How can I find the value of each variable in terms of $t$?

Answer 1

If $y=f(x)$ is a function of $x$ we can write parametric equations by writing $x=t$ and $y=f(t)$. So in your example we write $x=t$ and $y=3t$.