There are two buckets, A and B. Pour 50% of the water in bucket A into bucket B, which just fills bucket B (2/3). To fill bucket B up, 4kg of water is needed. How many kilograms of water is there?
有甲、乙两个水桶，把甲桶里的水的50%倒入乙桶，刚好装了乙桶的(2/3)，要把乙桶加满，还需4kg水，甲桶里原有水多少千克？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">4 / (1/3)</gadget>
<output>12</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(2/3) / (1/2)</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">12 * (4/3)</gadget>
<output>16</output>

<result>16</result>