Cara likes candles. She also likes mathematics and was thinking about using algebra to answer a question that she had about three of her candles. Her taller candle is 16 centimeters tall. Each hour it burns makes the candle lose 2.5 centimeters in height. Her short candle is 12 centimeters tall and loses 1.5 centimeters in height for each hour that it burns. Cara’s middle candle is 15 cm tall and burns at a rate of 2.25 centimeters in height for each hour that it burns. When will all candles be the 6cm tall?