Find the equivalent resistance between A and B. Also find the equivalent resistance between A and B if the two resistances of $$6R$$ are removed.
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PLACEHOLDER ANSWER - the question has two answers. On each side, the loop of three resistors $$R$$ (total $$3R$$) is in parallel with $$6R$$, giving $$2R$$ between each terminal and the top junction above it. The path through the top is then $$2R + 2R + 2R = 6R$$, in parallel with the direct $$12R$$, so $$R_{AB} = \frac{6R \times 12R}{18R} = 4R$$. Without the $$6R$$ resistors, each side is $$3R$$, the top path is $$3R + 2R + 3R = 8R$$, and $$R_{AB} = \frac{8R \times 12R}{20R} = 4.8R$$.