A piece of steel is (4/5) meters long, if (1/2) is used up, how many meters are left?
一根钢材长(4/5)米，如果用去(1/2)还剩下多少米．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</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">(4/5) * (1/2)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>