For a trapezoid, the upper base is 8 cm. If the upper base is increased by 3 cm, it is exactly equal to the lower base. Its two waists are 5 cm and 3 cm respectively. What is the perimeter of the trapezoid in cm?
一个梯形，上底是8厘米，如果把它的上底增加3厘米，正好与下底相等，它的两个腰分别是5厘米和3厘米，这个梯形的周长是多少厘米？
<gadget id="calculator">3 + 8</gadget>
<output>11</output>

<gadget id="calculator">8 + 11 + 5 + 3</gadget>
<output>27</output>

<result>27</result>