The upper base of an isosceles trapezoid is 4 cm, the lower base is 6 cm, and its circumference is 20 cm. How long is the waist of the isosceles trapezoid in cm?
一个等腰梯形的上底是4厘米，下底是6厘米，它的周长是20厘米，等腰梯形的腰长多少厘米？
<gadget id="calculator">20 - 4 - 6</gadget>
<output>10</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<result>5</result>