The height of a trapezoid is 10 cm, and the length of the upper base is three times the length of the lower base. If the upper base is reduced by 4 cm and the lower base is increased by 6 cm, a rectangle is formed. What is the area of the trapezoid in square centimeters?
一个梯形高10厘米，上底长是下底长的3倍，如果上底减少4厘米，下底增加6厘米，则成一个长方形，则梯形的面积是多少平方厘米．
<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">15 + 5</gadget>
<output>20</output>

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

<result>100</result>