(9/10) meters of iron bars, how many meters are left after (1/2) of them are used up?
(9/10)米的铁条，用去它的(1/2)后，还剩多少米．
<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

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

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

<gadget id="calculator">(9/10) * (1/2)</gadget>
<output>9/20 = around 0.45</output>

<result>9/20 = around 0.45</result>