Acircuit contains a 12 volt battery and two 3 ohm bulbs in series. calculate the current

If there are two bulbs in series, and each bulb has

                                                   resistance = 3 ohms,

then their total resistance in series is 6 ohms. 

When the series pair of bulbs is connected across the terminals
of the battery, the current through the circuit is

 Current = (voltage) / (resistance) 

               =  (12 volts) / (6 ohms)  =  2 amperes