The upper base of a trapezoid is 6 meters, the lower base is 14 meters, and the height is 30 meters. What is its area?
一个梯形的上底是6米，下底是14米，高30米，它的面积是多少．
<gadget id="calculator">6 + 14</gadget>
<output>20</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">20 * 15</gadget>
<output>300</output>

<result>300</result>