A rope is 10 meters long. After (1/5) is used up, (1/5) meter is used up. How many meters are left?
一根绳子长10米，用去(1/5)后，又用去(1/5)米，还剩多少米．
<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">10 * (4/5)</gadget>
<output>8</output>

<gadget id="calculator">8 - (1/5)</gadget>
<output>39/5 = around 7.8</output>

<result>39/5 = around 7.8</result>