Given an isosceles triangle, its apex angle is 40°, how many degrees are its two base angles?
已知一个等腰三角形，它的顶角是40°，那它的两个底角是多少度？
<gadget id="calculator">180 - 40</gadget>
<output>140</output>

<gadget id="calculator">140 / 2</gadget>
<output>70</output>

<result>70</result>