The upper base of the trapezoid is 5 decimeters, the lower base is 9 decimeters, and the height is 6 decimeters. What is its area?
梯形的上底是5分米，下底是9分米，高是6分米，它的面积是多少．
<gadget id="calculator">5 + 9</gadget>
<output>14</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">14 * 3</gadget>
<output>42</output>

<result>42</result>