The perimeter of an isosceles triangle is 78 cm, the length of one side is 25 cm, what is the length of the base in cm?
一个等腰三角形的周长是78厘米，一腰长25厘米，底边长是多少厘米．
<gadget id="calculator">78 - 25 - 25</gadget>
<output>28</output>

<result>28</result>