There is a bottle of 500ml of pure alcohol, 200ml is poured out, and 100ml of water is added, what is the alcohol content in the bottle at this time?
有一瓶500毫升的纯酒精，倒出200毫升，又加入了100毫升水，这时瓶内的酒精含量是多少．
<gadget id="calculator">500 - 200</gadget>
<output>300</output>

<gadget id="calculator">300 + 100</gadget>
<output>400</output>

<gadget id="calculator">300 / 400</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(3/4) * 1</gadget>
<output>3/4 = around 0.75</output>

<result>3/4 = around 0.75</result>