A trapezoidal vegetable field has an upper base of 6 meters, a height of 8 meters, and a height twice that of the lower base. How big is this vegetable field?
一块梯形菜地，上底是6米，高是8米，高是下底的2倍，这块菜地有多大？
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<gadget id="calculator">10 * 4</gadget>
<output>40</output>

<result>40</result>