Xiaohong bought a triangular scarf, one of its base angles is 50°, what is its top angle?
小红买了一条三角形的围巾，它的一个底角是50°，它的顶角是多少．
<gadget id="calculator">50 * 2</gadget>
<output>100</output>

<gadget id="calculator">180 - 100</gadget>
<output>80</output>

<result>80</result>