A base angle of an isosceles triangle is equivalent to (2/9) of the sum of the interior angles. How many degrees is the apex angle of this triangle?
一个等腰三角形的一个底角度数相当于内角和的(2/9)，这个三角形顶角是多少度？
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">180 * (2/9)</gadget>
<output>40</output>

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

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

<result>100</result>