The upper base of a trapezoid is 2.2 meters, the lower base is 2.8 meters, and the height is 1.8 meters. What is its area?
一个梯形的上底是2.2米，下底是2.8米，高是1.8米，它的面积是多少．
<gadget id="calculator">2.2 + 2.8</gadget>
<output>5</output>

<gadget id="calculator">1.8 / 2</gadget>
<output>0.9</output>

<gadget id="calculator">5 * 0.9</gadget>
<output>4.5</output>

<result>4.5</result>