A red scarf, its top angle is 100°, what is its bottom angle in degrees?
一条红领巾，它的顶角是100°，它的一个底角是多少度．
<gadget id="calculator">180 - 100</gadget>
<output>80</output>

<gadget id="calculator">80 / 2</gadget>
<output>40</output>

<result>40</result>