The upper base of a trapezoid is 10 cm, the lower base is 15 cm, and the height is 6 cm. What is its area in square centimeters?
一个梯形的上底是10厘米，下底是15厘米，高是6厘米，它的面积是多少平方厘米．
<gadget id="calculator">15 + 10</gadget>
<output>25</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">25 * 3</gadget>
<output>75</output>

<result>75</result>