After subtracting the numerator and denominator of (5/9), it can be roughly divided into (1/2).
(5/9)的分子、分母同时减去多少后，约分为(1/2)．
<gadget id="calculator">2 / 1</gadget>
<output>2</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * 9</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">5 - (9/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) / (1/2)</gadget>
<output>1</output>

<result>1</result>