A shopkeeper ordered 12 kg of premium coffee and some kg of regular coffee. The price of premium coffee per kg was three times that of regular coffee. Due to a billing mistake, the quantities of the two types were interchanged, which reduced the total bill by 30%. What was the ratio of the quantity of premium coffee to regular coffee in the original order?

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Accepted Answer

1. Let regular price be $R$. Then premium price is $3R$. Original cost = $12	imes3R + xR = (36+x)R$.
2. After swap, charged = $x	imes3R + 12R = (3x+12)R$.
3. Charged is 70% of original: $3x+12=0.7(36+x)$. So $2.3x=13.2$ and $x=132/23$.
4. Ratio premium:regular = $12:x = 12:(132/23)=276:132=23:11$.
FINAL_ANSWER: d

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