After increasing (1/2) of 20 kilograms, then reducing (1/2) kilograms, how many kilograms should it be?
20千克增加它的(1/2)后，再减少(1/2)千克，应该是多少千克．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 + (1/2)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">20 * (3/2)</gadget>
<output>30</output>

<gadget id="calculator">30 - (1/2)</gadget>
<output>59/2 = around 29.5</output>

<result>59/2 = around 29.5</result>