A rope, (7/10) meters are used for the first time, (7/10) is used for the second time, and (7/10) meters are left. How long is this rope in meters?
一根绳子，第一次用去(7/10)米，第二次用去(7/10)，还剩下(7/10)米．这根绳子全长多少米？
<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">(7/10) + (7/10)</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(7/5) / (3/10)</gadget>
<output>14/3 = around 4.666667</output>

<result>14/3 = around 4.666667</result>