Sal's Supermarket sells cases of twenty-four 12 oz-bottles of water for $15.50. Shopper's World sells 12-packs of 12-oz bottles of water for $8.15. Which store has the better price per bottle? Explain

answer:  

\boxed {\frac{1}{5}}  

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solution-

60 *   \frac{1}{5}   = 12

90 * \frac{1}{5} = 18

75 * \frac{1}{5} = 15

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hence, the answer would be \boxed {\frac{1}{5}}