The heater element of an electric kettle has a constant resistance of 105 and applied voltage of

Question:

The heater element of an electric kettle has a constant resistance of 105Ω and applied voltage of 240V.
1. Calculate time taken to raise the temperature of one liter of water from 15oC to 90oC assuming that only 80% of the power input to the kettle is usefully employed.
2. If the water equivalent of the kettle is 150g, find how long it will take to raise a second liter of water through the same temperature range immediately after the first time.
Please show all steps, I have calculated the answers but not sure of second answer