number is greater than 40% of 20 (1/2), find this number.
一个数比20的40%大(1/2)，求这个数．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">20 * (2/5)</gadget>
<output>8</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">8 + (1/2)</gadget>
<output>17/2 = around 8.5</output>

<result>17/2 = around 8.5</result>