The base angle of an isosceles triangle is 4 times the top angle, what is the base angle of this triangle?
一个等腰三角形底角是顶角的4倍，这个三角形底角是多少度．
<gadget id="calculator">1 + 4 + 4</gadget>
<output>9</output>

<gadget id="calculator">180 / 9</gadget>
<output>20</output>

<gadget id="calculator">4 * 20</gadget>
<output>80</output>

<result>80</result>