An object falls from the air, falls 4.9 meters in the first second, then falls 9.8 meters more than the previous second every second, and reaches the ground after 4 seconds. What was the original height of the object above the ground?
一个物体从空中落下，第一秒钟落下4.9米，以后每秒钟都比前一秒钟多落下9.8米，经过4秒钟到达地面．这个物体原来离地面的高度是多少米？
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">3 * 9.8</gadget>
<output>29.4</output>

<gadget id="calculator">4.9 + 29.4</gadget>
<output>34.3</output>

<gadget id="calculator">4.9 + 34.3</gadget>
<output>39.2</output>

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

<gadget id="calculator">39.2 * 2</gadget>
<output>78.4</output>

<result>78.4</result>