Solution A and solution B contain 40% and 36% alcohol respectively. To prepare 12 liters of a solution containing 39% alcohol, how many liters of solution A should be used at least?
甲、乙两溶液含酒精分量分别为40%及36%．若要配制成含酒精分量为39%的溶液12升，问至少要用甲溶液多少升？
<gadget id="calculator">4.68 - 4.32</gadget>
<output>0.36</output>

<gadget id="calculator">0.4 - 0.36</gadget>
<output>0.04</output>

<gadget id="calculator">0.36 / 0.04</gadget>
<output>9</output>

<result>9</result>