Problem with current and parallel resistors. Please help! Ok, I've got this homework problem that I'm somewhat stuck with. The problem relates to the picture below: I've got to figure out the total resistivity (done that), total current (done that), the current through the 21 ohm resistor and the voltage drop at the 21 ohm resistor. So I figured I'd find the current first, but I've got a problem. Once the circuit comes back together from the 4 and 17 ohm resistors, how do I calculate the current? I can't find any examples in my book of the resistance of a resistor that comes after a parallel circuit that has been closed again. Please help!