In my bath tub, there is a cold water tap that flows water in at 20 litres per minute.

There is also a hot water tap that flows water in at 12 litres per minute.

There is also a hole at the bottom of the bath tub which removes water from the tub at 15 litres per minute.

The bath holds a maximum of 510 liters.

I turn both faucets on, but forget to put the plug in and that lets the water go out of the hole. How many minutes does it take for the bath to overflow?