How many milliliters of water is needed to make 200 milliliters of 75% alcohol?
制成含75%的酒精200毫升，需要水多少毫升？
<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">200 * (1/4)</gadget>
<output>50</output>

<result>50</result>