The upper base of a trapezoid is 8 cm, the lower base is 30 cm, and the height is 1 decimeter. What is its area?
一个梯形的上底是8厘米、下底是30厘米，高是1分米，它的面积是多少．
<gadget id="calculator">8 + 30</gadget>
<output>38</output>

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

<gadget id="calculator">38 * 1 * 5</gadget>
<output>190</output>

<result>190</result>