Parallel and Series circuits

So I learned about parallel and series circuits and the difference between the two. A series circuit is a circuit in which resistors are arranged in a chain, so the current has only one path to take. The current is the same through each resistor. The total resistance of the circuit is found by simply adding up the resistance values of the individual resistors: equivalent resistance of resistors in series : R = R₁ + R₂ + R₃ + ... etc. A parallel circuit is a circuit in which the resistors are arranged with their heads connected together, and their tails connected together. The current in a parallel circuit breaks up, with some flowing along each parallel branch and re-combining when the branches meet again. The voltage across each resistor in parallel is the same. Too bad the quiz problems for these are so difficult. There is one problem that is so hard to figure out. It's not even a parallel or a series circuit, it the INCEPTION circuit. Its got a parallel within a series within a parallel and a random diamond shape thrown in there. What is also confusing is that the current is the same in a series, but not in a parallel and the voltage is the same in a parallel and not in a series. And i'm pretty sure to find the resistance of the parallel its the equation: Req=1/R₁ +1/ R_{2, etc.}