Use a rope to measure a bamboo pole. The rope is 1.8 meters longer than the bamboo pole. Fold the rope in half and measure the bamboo pole. The bamboo pole is 2.2 meters longer than the rope. How many meters is the rope?
用一根绳子量一根竹竿，绳子比竹竿长1.8米，把绳子对折后量竹竿，竹竿比绳子长2.2米，绳子有多少米．
<gadget id="calculator">1.8 + 2.2</gadget>
<output>4</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<result>8</result>