The perimeter of an isosceles triangle is 12 centimeters, one of its sides is 5 centimeters, what is the length of its base in centimeters?
一个等腰三角形的周长是12厘米，它的一条腰长是5厘米，它的底边长是多少厘米．
<gadget id="calculator">5 + 5</gadget>
<output>10</output>

<gadget id="calculator">12 - 10</gadget>
<output>2</output>

<result>2</result>