I am a student in 10th grade and our teacher gave us this schematic to work with (Remade with circuit lab):
He asked us to find the equivalent resistance of the circuit. Based on my calculations, 24 Ohms should be the right answer. Apparently my teacher disagreed and told us it was around 2.5 Ohms or so.
I don't know which answer is the correct one, but I am fairly convinced that mine is the most correct one. Since even if my calculations of the series-parallel resistors are wrong, the minimum resistance is going to be 20 Ohms (R1 + R7).