A plastic plate is an isosceles triangle, and one of its base angles is 54°, so how many degrees is its top angle?
一块塑料板是一个等腰三角形，它的一个底角是54°那么它的顶角是多少度？
<gadget id="calculator">54 * 2</gadget>
<output>108</output>

<gadget id="calculator">180 - 108</gadget>
<output>72</output>

<result>72</result>