The perimeter of an isosceles triangle is 48 cm, and the base is 3 cm longer than one of its waists. Then, how long is its base in cm?
等腰三角形的周长是48厘米，底边比它的一条腰长3厘米，那么，它的底边长多少厘米？
<gadget id="calculator">48 - 3</gadget>
<output>45</output>

<gadget id="calculator">45 / 3</gadget>
<output>15</output>

<gadget id="calculator">15 + 3</gadget>
<output>18</output>

<result>18</result>