After drinking half of a bottle of Wine King, the weight of the bottle is 650 grams. If you drink the rest of the wine (2/5), the weight of the bottle is still 550 grams. How much does the bottle weigh?
一瓶酒王师傅喝了一半后连瓶重650克，如果再喝去剩下的酒的(2/5)，连瓶重还有550克，这个瓶子重多少克．
<gadget id="calculator">650 - 550</gadget>
<output>100</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/2) * (2/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">100 / (1/5)</gadget>
<output>500</output>

<gadget id="calculator">500 / 2</gadget>
<output>250</output>

<gadget id="calculator">650 - 250</gadget>
<output>400</output>

<result>400</result>