If the sum of the upper and lower bases of a trapezoid is 25 and the height is 12, what is the area of the trapezoid?
一个梯形的上下底的和是25，高是12，则梯形的面积是多少．
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">25 * 6</gadget>
<output>150</output>

<result>150</result>