For a wire, first use up (1/5) of its full length, and then use up (1/5) meter. At this time, there are still 9 meters left. How long is this wire in meters?
一根电线，先用去全长的(1/5)，再用去(1/5)米，这时还剩下9米，原来这根电线长多少米？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">9 + (1/5)</gadget>
<output>46/5 = around 9.2</output>

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

<gadget id="calculator">(46/5) / (4/5)</gadget>
<output>23/2 = around 11.5</output>

<result>23/2 = around 11.5</result>