Try this GRE question that tests your understanding of the equation of straight lines and the area of triangle in the $xy$-coordinate plane.

A vertical line divides the triangle with vertices $(0, 0), (1,1)$ and $(9, 1)$ in the $xy-$plane into two regions of equal area. The equation of the line is $x=$

- $\quad 2.5 $
- $\quad 3.0 $
- $\quad 3.5 $
- $\quad 4.0 $
- $\quad 4.5 $