A green and red bar are shown. The green bar has a height of 2 and casts a shadow of 3 on the floor. The red bar casts a shadow of 6 on the floor which continues to a height of 4 on a parallel wall.
What is the height of the red bar?
You can assume the light source is distant, the floors and walls are perfectly flat, and the floor is perpendicular to the bars and walls.