Lime, sulfur, and water are mixed according to the ratio of 1:2:10 to 390 kg of pesticides, how many kg of water is needed.
石灰、硫磺、水按1：2：10配置农药390千克，则需要水多少千克．
<gadget id="calculator">1 + 2 + 10</gadget>
<output>13</output>

<gadget id="calculator">10 / 13</gadget>
<output>10/13 = around 0.769231</output>

<gadget id="calculator">390 * (10/13)</gadget>
<output>300</output>

<result>300</result>