Dad bought Xiaohong an isosceles triangle kite. The base angle of one of them is 70°, what is the top angle?
爸爸给小红买了一个等腰三角形的风筝．它的一个的底角是70°，顶角是多少．
<gadget id="calculator">70 * 2</gadget>
<output>140</output>

<gadget id="calculator">180 - 140</gadget>
<output>40</output>

<result>40</result>