bottle of alcohol, when half of it is used, the weight of the bottle is 700 grams; if 1/3 of the alcohol is used, the weight of the bottle is 800 grams. Find the weight of the bottle.
一瓶酒精，当用去一半后，连瓶重700克；如果用去酒精的(1/3)后，连瓶共重800克．求瓶子的重量．
<gadget id="calculator">800 - 700</gadget>
<output>100</output>

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

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">100 / (1/6)</gadget>
<output>600</output>

<gadget id="calculator">600 * (1/2)</gadget>
<output>300</output>

<gadget id="calculator">700 - 300</gadget>
<output>400</output>

<result>400</result>