40 kilograms increase (1/10) and then decrease (1/10), what is the result in kilograms?
40千克增加(1/10)后又减少(1/10)，结果是多少千克．
<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">40 * (11/10) * (9/10)</gadget>
<output>198/5 = around 39.6</output>

<result>198/5 = around 39.6</result>