The heater element of an electric kettle has a constant resistance of 105 and applied voltage of 240V. 3.1 Calculate time taken to raise the

The heater element of an electric kettle has a constant resistance of 105Ω and applied voltage of 240V.
3.1 Calculate time taken to raise the temperature of one litre of water from 15oC to 90oC assuming that only 80% of the power input to the kettle is usefully employed. (5)
3.2 If the water equivalent of the kettle is 150g, find how long it will take to raise a second litre of water through the same temperature range immediately after the first time.