In the circuit shown in the figure, two resistors R1 and R2 have been connected in series to an ideal cell. When a voltmeter is connected across R1 its reading is V1 = 4.0 volt and when the same voltmeter is connected across R2 its reading is V2=6.0 volt. The reading of the voltmeter when it is connected across the cell is V3 = 12.0 volt. Find the actual across R1 in the circuit.