Let $L$, $G \subset \mathbb{P}^2$ be lines. Show that there exists a projective change of coordinates $T$, such that $T(L)=G$.
This is how we defined a projective change of coordinates in $\mathbb{P}^2$:
If $S$: $\mathbb{A}^3 \to\mathbb{A}^3$ is a linear affine change of coordiantes, then $S$ maps lines through the origin to lines through the origin again. So $S$ induces a map $S'$: $\mathbb{P}^2 \to\mathbb{P}^2$ which is called a projective change of coordinates.
I am not sure how to tackle this problem since I haven't got much more than the definition. I would appreciate any help.