Li Hong used to weigh 40 kilograms, but lost 10% of his weight after suffering from an illness. Later, he insisted on physical exercise and gained another 10% of his weight. How many kilograms does Li Hong weigh now?
李红原来体重40千克，生了一场病后体重减轻了10%，后来他坚持体育锻炼，体重又增加了了10%，李红现在的体重是多少千克？
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

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

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

<gadget id="calculator">40 * (9/10) * (11/10)</gadget>
<output>198/5 = around 39.6</output>

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