The upper base of the trapezoid is 1.8 meters, the lower base is 2.2 meters, and the height is 30 decimeters. What is its area in square meters?
梯形上底1.8米，下底2.2米，高30分米，它的面积是多少平方米．
<gadget id="calculator">1.8 + 2.2</gadget>
<output>4</output>

<gadget id="calculator">30 / 10 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">4 * (3/2)</gadget>
<output>6</output>

<result>6</result>