1. The problem statement, all variables and given/known data In the circuit shown in the figure http://s3.amazonaws.com/answer-board-image/ffa3225e-0730-480c-8ed0-f417490d6b96.jpeg[/COLOR] , the current in the 20.0-V battery is 5.00A in the direction shown and the voltage across the 8.00-Ω resistor is 16.0V , with the lower end of the resistor at higher potential. Find the emf of the battery . Part B Find the polarity of the battery . the upper terminal - the upper terminal + Part C Find the current through the 200.0- battery. Part D Find the direction of the current through the 200.0- battery. The current through the 200.0 battery is in the direction from the - to the + terminal. The current through the 200.0 battery is in the direction from the + to the - terminal. Part E Find the resistance . 2. Relevant equations Kirrchoff's Laws 3. The attempt at a solution I know how to use the laws well. I thought that since there is a pd of 16 across the 8 ohm resistor so there is a 2A moving up this line. When it came to the junction I'm lost. In the SM, they say that we can combine the unknown R as parallel ones. We can also combine the 30 and 20 ohm resistors as parallel. HOW IS THIS POSSIBLE? ... We can never assume they are parallel. I need clarification!