1. The problem statement, all variables and given/known data http://imgur.com/DuBgK 2. Relevant equations I1=I2+I3 Sum of the directed potential differences around any closed loop equals zero 3. The attempt at a solution I worked out the total resistance which came out to be 4.5Ω [3 + 1/(1/6+1/2)] But now I don't know which voltage to use to calculate the total current flow in the circuit. The confusion I have is the +18V, I don't understand where it comes from hence I am confused as to what amount of potential to use.. Thanks in advance.