Two barrels of water weigh 22 kg. After 1 kg of water in the small bucket is used, the ratio of the remaining water to the water in the large bucket is 2:5. How many kilograms of water were originally contained in the small bucket?
两桶水共有22千克．小桶的水用去1千克后，剩下的与大桶中的水比是2：5．小桶里原来装有多少千克水？
<gadget id="calculator">22 - 1</gadget>
<output>21</output>

<gadget id="calculator">2 + 5</gadget>
<output>7</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">21 * (2/7)</gadget>
<output>6</output>

<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<result>7</result>