The sum of the upper and lower bases of a trapezoid is 60 cm and the height is 4 cm. What is the area of the trapezoid in square centimeters?
一个梯形的上下底之和是60厘米，高是4厘米，这个梯形的面积是多少平方厘米．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">60 * 2</gadget>
<output>120</output>

<result>120</result>