The red rope is 14 meters, the red rope is 2 meters shorter than the green rope, and the average length of the green rope and the black rope is 3 meters longer than the red rope, so how long is the black rope in meters?
红绳子是14米，红绳子比绿绳子短2米，绿绳子与黑绳子的平均长度比红绳子长3米，那么黑绳子的长度是多少米？
<gadget id="calculator">14 + 3</gadget>
<output>17</output>

<gadget id="calculator">17 * 2</gadget>
<output>34</output>

<gadget id="calculator">14 + 2</gadget>
<output>16</output>

<gadget id="calculator">34 - 16</gadget>
<output>18</output>

<result>18</result>