after the electricity went out mr.choi took out two candles, both were the same lengths but the label on candle A said it would burn for 4 hours while the label on candle B said it would burn for 5 hours. mr.choi lit both candles at the same time and let them burn until the electricity was back. he saw that what was left on one candle was exactly four times what was left on the other candle. how long was the electricity out? (need to solve with an algebraic formula)

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