A bottle filled with water weighs 640 grams. When half of the water is poured out of the bottle, the bottle and water weigh 380 grams. How many grams does the bottle weigh?
一个瓶子装满水后重640克，从瓶子中倒出一半水后，瓶子和水重380克，瓶子重多少克？
<gadget id="calculator">640 - 380</gadget>
<output>260</output>

<gadget id="calculator">260 * 2</gadget>
<output>520</output>

<gadget id="calculator">640 - 520</gadget>
<output>120</output>

<result>120</result>