After increasing (1/4) 20 tons, then decreasing (1/5), what is the result?
20吨增加(1/4)后，再减少(1/5)，结果是多少．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">20 * (5/4) * (4/5)</gadget>
<output>20</output>

<result>20</result>