A trapezoidal plank, the upper base is 2.5 meters, the lower base is twice the upper base less than 2 meters, and the height is 1 meter. What is the area of the trapezoidal plank?
一块梯形木板，上底是2.5米，下底是上底的2倍少2米，高是1米，这个梯形木板的面积是多少．
<gadget id="calculator">2.5 * 2</gadget>
<output>5</output>

<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">2.5 + 3</gadget>
<output>5.5</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">5.5 * (1/2)</gadget>
<output>2.75</output>

<result>2.75</result>