I = 3.4 Amp
V = 220 Volts
Electric iron has a resistance = R
V = I R
=> R = V / I = 220 / 3.4
= 64.7 Ω
When the electric iron is connected to a 110 Volts supply,
I = V / R = 110 / 64.7 = 1.7 Amp.
Alternately, As the voltage becomes half of its value, the current becomes half of its value, as the current is directly proportional to the potential difference across a conductor or a resistor. This is as per Ohm's law.