If the sum of the upper and lower bases of a trapezoid is 15 cm and the height is 8 cm, what is the area in square centimeters?
一个梯形上底与下底的和是15厘米，高是8厘米，面积是多少平方厘米．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<result>60</result>