A factory has 2 tons of steel, how many tons are left after (1/5) is used up?
某工厂有2吨钢材，用掉(1/5)以后，还剩下多少吨．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">2 * (4/5)</gadget>
<output>8/5 = around 1.6</output>

<result>8/5 = around 1.6</result>