It takes 3 seconds for a small ball to roll from A to B. The speed in the first second is 15.5 meters, and every second thereafter decreases by 3.4 meters from the previous second. What is the distance from A to B?
一个小球从甲处滚到乙处共用了3秒钟，第一秒钟的速度是15.5米，以后每秒比前一秒减少3.4米，甲处到乙处的距离是多少？
<gadget id="calculator">15.5 - 3.4</gadget>
<output>12.1</output>

<gadget id="calculator">15.5 - 3.4 - 3.4</gadget>
<output>8.7</output>

<gadget id="calculator">15.5 + 12.1 + 8.7</gadget>
<output>36.3</output>

<result>36.3</result>