Explanation:
Current output at the battery will be current of entire circuit, while the current through each bulb in the parallel circuit is the total current circuit.
So, current output through power supply is i and current through each component be [tex]i_1, i_2 , i_3[/tex] considering only three component.
Then in a parallel circuit
[tex]i = i_1+i_2+i_3[/tex]