bottle is full of water, if half of it is poured out, the remaining water will weigh 750g even with the bottle; if it is poured out (1/3), the remaining water will weigh 900g even with the bottle. How many grams does the empty bottle weigh?
一个瓶子里装满了水，如果倒掉一半，剩下的水连瓶重750g；如果倒掉(1/3)，剩下水连瓶重900g．空瓶子重多少克？
<gadget id="calculator">900 - 750</gadget>
<output>150</output>

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

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

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

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

<gadget id="calculator">150 / (1/6)</gadget>
<output>900</output>

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

<gadget id="calculator">900 * (1/2)</gadget>
<output>450</output>

<gadget id="calculator">750 - 450</gadget>
<output>300</output>

<result>300</result>