The perimeter of an isosceles triangle is 27 cm, and one of its sides is 10 cm long. What is the length of the base of this isosceles triangle?
一个等腰三角形周长是27厘米，它的一条腰长10厘米，这个等腰三角形的底边长多少厘米？
<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">27 - 20</gadget>
<output>7</output>

<result>7</result>