Dad bought a red scarf for Xiaohong. One of its bottom angles is 30°. What is its top angle?
爸爸给小红买了一条红领巾，它的一个底角是30°，它的顶角是多少度？
<gadget id="calculator">30 * 2</gadget>
<output>60</output>

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

<result>120</result>