If the perimeter of an isosceles triangle is 84 cm and the length of the base is 24 cm, what is the length of one of its sides in cm?
如果一个等腰三角形的周长是84厘米，底边长是24厘米，它的一条腰长是多少厘米．
<gadget id="calculator">84 - 24</gadget>
<output>60</output>

<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<result>30</result>