There are 20 kilograms of apples, ate (1/2) on the first day, and the rest (1/2) on the second day, how many kilograms are left?
有20千克苹果，第一天吃了(1/2)，第二天吃了剩下的(1/2)，还剩多少千克．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * (1/2)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/2) - (1/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">20 * (1/4)</gadget>
<output>5</output>

<result>5</result>