A rope (8/9) meters, (3/4) of it is used up, and there are ((())/(())) left, and ((())/(())) meters are left, if Use up (1/4) meter, how many meters are left.
一根绳子(8/9)米，用去它的(3/4)，还剩((())/(()))，还剩((())/(()))米，如果用去(1/4)米，还剩多少米．
<gadget id="calculator">8 / 9</gadget>
<output>8/9 = around 0.888889</output>

<gadget id="calculator">3 / 4</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">(8/9) - (1/4)</gadget>
<output>23/36 = around 0.638889</output>

<result>23/36 = around 0.638889</result>