If you drink (1/2) a cup of 20 liters of milk and fill it up with water, what is the concentration of the milk
把一杯20升的牛奶喝掉(1/2)杯，再用水填满，则牛奶的浓度是多少
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) / 20</gadget>
<output>1/40 = around 0.025</output>

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

<gadget id="calculator">20 * (1/40) * 1</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>