The waist length of an isosceles trapezoid is 4 cm, the lower base is 6 cm, and the upper base is half of the lower base. Find the perimeter of the trapezoid.
一个等腰梯形的腰长为4厘米，下底为6厘米，上底是下底的一半，求这个梯形的周长．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">3 + 6 + 8</gadget>
<output>17</output>

<result>17</result>