There are three colored ropes, red, yellow and blue. The red rope is 7 meters longer than the yellow rope, and the blue rope is 5 meters shorter than the yellow rope. What is the distance between the red string and the blue string in meters?
有红，黄，蓝三根彩绳，红绳比黄绳长7米，蓝绳比黄绳短5米．红绳和蓝绳相差多少米．
<gadget id="calculator">7 + 5</gadget>
<output>12</output>

<result>12</result>