The length of the first rope is a meter, the length of the second rope is 13 meters, and the length of the second rope is 6 meters longer than twice the length of the first rope.
第一根绳子长a米，第二根绳子长13米，第二根的长度比第一根的2倍还要多6米．
<gadget id="calculator">13 - 6</gadget>
<output>7</output>

<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<result>7/2 = around 3.5</result>