Two measuring cups, A and B, each contain the same amount of water. After pouring 20 grams from cup A into cup B, the weight of water in cup A is equivalent to (4/5) that of water in cup B. How many grams of water is there in each cup? ．
甲、乙两个量杯内各盛有相同数量的水，从甲杯倒入乙杯20克后，甲杯水的重量相当于乙杯水的(4/5)，原来每杯有水多少克．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">2 / (1/5)</gadget>
<output>10</output>

<gadget id="calculator">20 * 10</gadget>
<output>200</output>

<gadget id="calculator">200 - 20</gadget>
<output>180</output>

<result>180</result>