There is some water stored in a container, and now (2/7) of the water is poured out, and the remaining water and the container weigh 7.2 kg; if the remaining water (2/3) is poured out, then the water and the container The ratio of the weight to the original weight is 1:3 (before pouring out the water for the first time). So how many kilograms of water is in the original container?
一个容器内贮有一些水，现在倒掉其中(2/7)的水，剩下的水和容器共重7.2千克；若再倒掉剩下水的(2/3)，这时水和容器的重量与原来重量的比为1：3(第一次倒掉水之前)．那么原来容器有多少千克的水？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">7.2 * (1/3)</gadget>
<output>2.4</output>

<gadget id="calculator">7.2 - 2.4</gadget>
<output>4.8</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(5/7) * (2/3)</gadget>
<output>10/21 = around 0.47619</output>

<gadget id="calculator">(5/7) * (1/3)</gadget>
<output>5/21 = around 0.238095</output>

<gadget id="calculator">(1/3) - (5/7) - (5/21)</gadget>
<output>-13/21 = around -0.619048</output>

<gadget id="calculator">(5/7) + (10/21) + (-13/21)</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">4.8 / (4/7)</gadget>
<output>8.4</output>

<result>8.4</result>