Help with simple electric circuits ?

In the circuit R1=3 , R2=4 , R3=12 , Vt=12 , Rt=6 and I need to find I1 I2 I3 and V1 V2 V3. The circuit is a rectangle with two parallel lines, the first resistor is connected in series and then there is one resistor on each parallel line. Three resistors in total. Please help! :)