You may get the current (Ampere) dividing the power (Watt) by the voltage (Volt), but this is true only for DC or a pure resistive and linear AC circuit without sources.
Otherwise you need more information — the power factor, or the circuit impedance (for a linear circuit, and without sources in the load), or the circuit details.
(contrary to what was said up to now by others).
However (I releat myself) if your load is just a heater (without fan), or another resistive load, dividing power (Watt) by voltage (Volt) will do it. It will not work for motors, transformer with load, and many other loads.
simple divide 3000 by 240 to get amps. watts divided by volts equals amps.
volt x amps is watts
its ohms lawif 2 values are know the third can be calculated.