A bottle of beverages weighs 450 grams in total. After drinking half of the bottles, the total weight of the bottles is 250 grams. How many grams does the bottle weigh?
一瓶饮料饮料，连瓶共重450克，喝去一半后连瓶共重250克，饮料瓶重多少克．
<gadget id="calculator">450 - 250</gadget>
<output>200</output>

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

<gadget id="calculator">450 - 400</gadget>
<output>50</output>

<result>50</result>