There are two wires, one is 21 meters long and the other is 18 meters long. After cutting the two wires to the same length, the remaining length ratio of the two wires is 10:7. How long is the cut section?
有两根电线，一根长21米，另一根长18米，把这两根电线都剪下同样长的一段以后，那么这两根电线剩下的长度比是10：7．剪下的一段有多长？
<gadget id="calculator">10 / 7</gadget>
<output>10/7 = around 1.428571</output>

<gadget id="calculator">(10/7) * 18</gadget>
<output>180/7 = around 25.714286</output>

<gadget id="calculator">(180/7) - 21</gadget>
<output>33/7 = around 4.714286</output>

<gadget id="calculator">(10/7) - 1</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(33/7) / (3/7)</gadget>
<output>11</output>

<result>11</result>