For a simple fraction, if 1 is added to the numerator, the fraction is (1/2); if 1 is subtracted from the numerator, the fraction is (1/4). What is the fraction?
一个最简分数，若分子加上1，约分得(1/2)；若分子减去1，约分得(1/4)，这个分数是多少．
<gadget id="calculator">2 + 4</gadget>
<output>6</output>

<gadget id="calculator">4 - 2</gadget>
<output>2</output>

<gadget id="calculator">6 / 2 / 8</gadget>
<output>3/8 = around 0.375</output>

<result>3/8 = around 0.375</result>