A liquid medicine is prepared from powder and water in a mass ratio of 1:8. To prepare 18 kg of this potion, how many kg of powder is needed.
一种药液是由药粉和水按照1：8的质量比配制而成的．配制这种药水18千克，需要药粉多少千克．
<gadget id="calculator">1 + 8</gadget>
<output>9</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">18 * (1/9)</gadget>
<output>2</output>

<result>2</result>