There is a trapezoid, the upper base is three times the lower base, and the height is 10 cm. If the upper base is subtracted by 4 cm and the lower base is increased by 6 cm, it becomes a rectangle. Find the area of the original trapezoid.
有一个梯形，上底是下底的3倍，高是10厘米，如果上底减去4厘米，下底增加6厘米，变成长方形．求原梯形的面积．
<gadget id="calculator">4 + 6</gadget>
<output>10</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<gadget id="calculator">5 + 15</gadget>
<output>20</output>

<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<result>100</result>