A ball falls from a high place and falls to the ground in 2 seconds. It falls 3.5 meters in the first second, and falls 5.4 meters more in the second second than in the first second. How far is the ball from the ground before it falls?
一个皮球从高处下落，经2秒钟落地，第一秒下来3.5米，第二秒比第一秒多落下5.4米．这个皮球下落前离地面多少米？
<gadget id="calculator">3.5 + 5.4</gadget>
<output>8.9</output>

<gadget id="calculator">3.5 + 8.9</gadget>
<output>12.4</output>

<result>12.4</result>