Subtract (1/5) from 1, and then subtract (3/4), how much is it.
从1里面减去(1/5)，再减去(3/4)，得多少．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">1 - (1/5) - (3/4)</gadget>
<output>1/20 = around 0.05</output>

<result>1/20 = around 0.05</result>