Xiao Ming discovered that the red scarf is an isosceles triangle with a base angle of 30°. Do you know how many degrees the top angle of the red scarf is?
小明发现：红领巾是一个等腰三角形，底角是30°．你知道红领巾的顶角是多少度吗？
<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<gadget id="calculator">180 - 60</gadget>
<output>120</output>

<result>120</result>