What the problem says:
When a screen is placed $3 m$ from a projector, the picture occupies $3 m^2$. How large will the picture be when the projector is $5 m$ from the screen?
My direct answer would be $5 m^2$, but it seems too easy to be true. I am curious about what the answer would be, or how to do it - it is not something critical since I am doing this in my free time.