A carton of milk, drank (2/5), how much more is left than drank?
一盒牛奶，喝了(2/5)，剩下的比喝了的多多少？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(3/5) - (2/5)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>