A cup is filled with water, even the cup weighs 500 grams in total. Pour out half of the water, and even the cup weighs a total of 300 grams. How many grams does this cup weigh? How many grams
一个杯子里装满了水，连杯称一共500克．倒掉水的一半，连杯称一共300克．这只杯子重多少克？多少克
<gadget id="calculator">500 - 300</gadget>
<output>200</output>

<gadget id="calculator">200 * 2</gadget>
<output>400</output>

<gadget id="calculator">500 - 400</gadget>
<output>100</output>

<result>100</result>