Baffling Bath Water Puzzle

The Puzzle:

Baffling Bath Water
The cold faucet in my bath lets the water in at the rate of 15 litres per minute.
The hot faucet fills the bath at the rate of 10 liters per minute.
The plug hole lets the water out of the bath at the rate of 12 liters per minute.

The bath holds a maximum of 520 liters.

I turn both faucets on, but forget to put the plug in. How many minutes does it take for the bath to overflow?
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