The width of a rectangular hall is ½ of its length

The width of a rectangular hall is ½ of its length. If the area of the hall is 450 sq.m, what is the difference between its length and breadth?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #23385