For an isosceles triangle billboard, one of its base angles is 65°, what is its top angle?
一个一块等腰三角形广告牌，它的一个底角是65°，它的顶角是多少度？
<gadget id="calculator">65 * 2</gadget>
<output>130</output>

<gadget id="calculator">180 - 130</gadget>
<output>50</output>

<result>50</result>