The innermost runway on the school playground is 400 meters long, and each track is 1.25 meters wide. If there is a 400-meter race, how many meters is the difference between the starting line of the second runway and the first runway (take 3 for π)
学校操场最内圈跑道长400米，每条跑道宽1.25米，如果进行400米赛跑，第二跑道的起跑线与第一跑道相差多少米(π取3)
<gadget id="calculator">3 * 1.25 * 2</gadget>
<output>7.5</output>

<result>7.5</result>