20 kilometers increase its (1/10) and then reduce its (1/10) how many kilometers.
20千米增加它的(1/10)后再减少它的(1/10)是多少千米．
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 + (1/10)</gadget>
<output>11/10 = around 1.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">20 * (11/10) * (9/10)</gadget>
<output>99/5 = around 19.8</output>

<result>99/5 = around 19.8</result>