The upper base of a trapezoid is 4m, the lower base is 10m, and the height is half of the upper base. What is the area of the trapezoid?
一个梯形的上底是4m，下底是10m，高是上底的一半，这个梯形的面积是多少．
<gadget id="calculator">4 + 10</gadget>
<output>14</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">14 * 1</gadget>
<output>14</output>

<result>14</result>