The sum of the upper and lower bases of a trapezoid is 24cm, and the height is 10cm. What is its area in cm**2.
一个梯形上、下底之和是24cm，高是10cm，它的面积是多少cm**2．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">24 * 5</gadget>
<output>120</output>

<result>120</result>