An object falls from a high altitude and falls to the ground after 4 seconds. It is known that the falling distance in the first second is 4.9 meters, and the falling distance in each subsequent second is 0.98 meters more than the previous second. How many meters was this object from the ground before it fell?
一个物体从高空落下，经过4秒后落地，已知第1秒下落的距离是4.9米，以后每一秒下落的距离都比前一秒多0.98米，这个物体在下落前距地面多少米？
<gadget id="calculator">0.98 * 3</gadget>
<output>2.94</output>

<gadget id="calculator">4.9 + 4.9 + 2.94</gadget>
<output>12.74</output>

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

<gadget id="calculator">12.74 * 2</gadget>
<output>25.48</output>

<result>25.48</result>