How to find the current in this circuit?
One way to do this systematically is to write some equations in terms of mesh currents. I1 flows in the right hand mesh in an anticlockwise direction and acts upon R3. I2 flows anticlockwise in the central mesh and acts upon R2, R3 and R4. Finally I3 flows in the left hand mesh and acts upon R2 and R2. I1 and I2 are unknown.
The next step is to write an equation based on the fact that the sum of voltages around the left hand mesh must equal zero. Same for central mesh. You are left with 2 simultaneous equations with 2 unknowns so you can solve for I1 and I2.