The perimeter of an isosceles triangle is 86 cm, and the length of one side is 28 cm. What is the length of the base of this triangle in cm?
一个等腰三角形的周长是86厘米，一条腰长28厘米，这个三角形的底边长是多少厘米？
<gadget id="calculator">28 * 2</gadget>
<output>56</output>

<gadget id="calculator">86 - 56</gadget>
<output>30</output>

<result>30</result>