Here are the answers and Cheats to Escape Room: Math Doors Door 83. If you need help with other levels check our Escape Room Math Doors Page.
Hint – 1 Cat takes 7 minutes to kill 1 Rat.
Solution – 10 A cat kill 1 rat in 7 min. in 49 min a cat can kill 7 rats. 10 cats will be able to kill 70 rats in 49 min.