The upper base of a trapezoid is 12.2 cm, the lower base is 38.8 cm, and the height is 12 cm. What is the area in square centimeters?
一个梯形的上底是12.2厘米，下底是38.8厘米，高是12厘米，面积是多少平方厘米？
<gadget id="calculator">12.2 + 38.8</gadget>
<output>51</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">51 * 6</gadget>
<output>306</output>

<result>306</result>