A bucket of salt water, the ratio of salt to water is 2:7, there is 35 kg of water in this bucket of salt water, how many kg of salt is there?
一桶盐水，盐和水的比是2：7，这桶盐水中水有35千克，盐有多少千克？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(2/7) * 35</gadget>
<output>10</output>

<result>10</result>