The upper base of an isosceles trapezoid is 3 cm, the lower base is 5 cm, and the waist is 1 cm longer than the lower base. What is the perimeter of this isosceles trapezoid?
一个等腰梯形的上底是3厘米，下底是5厘米，腰比下底长一厘米，这个等腰梯形的周长是多少？
<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<gadget id="calculator">3 + 5 + 12</gadget>
<output>20</output>

<result>20</result>