The toffee is 10.20 yuan per kilogram, and the halva is 8.20 yuan per kilogram. If 8 kilograms of toffee is mixed with how many kilograms of halva, the mixed sugar can be 9 yuan per kilogram.
奶糖每千克10.20元，酥糖每千克8.20元，用8千克奶糖与多少千克酥糖混合，可使混合后的糖每千克9元．
<gadget id="calculator">10.2 * 8</gadget>
<output>81.6</output>

<gadget id="calculator">8 * 9</gadget>
<output>72</output>

<gadget id="calculator">81.6 - 72</gadget>
<output>9.6</output>

<gadget id="calculator">9 - 8.2</gadget>
<output>0.8</output>

<gadget id="calculator">9.6 / 0.8</gadget>
<output>12</output>

<result>12</result>