91. A wild rabbit escapes 100 steps before the hunting dog starts to chase it. The rabbit runs 8 steps in the distance the hunting dog runs 3 steps, and in the time the hunting dog runs 4 steps, the rabbit can run 9 steps. The hunting dog has to run at least $\qquad$ steps to catch up with the rabbit.
Reference answer: 240

Exam point: Travel problem - hunting dog chasing rabbit