A trapezoidal swimming pool has an upper bottom of 8 meters, a lower bottom of 12 meters, and a height of 15 meters. What is the area in square meters?
一个梯形游泳池，上底8米，下底12米，高15米，占地面积是多少平方米．
<gadget id="calculator">8 + 12</gadget>
<output>20</output>

<gadget id="calculator">15 / 2</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">20 * (15/2)</gadget>
<output>150</output>

<result>150</result>