In an isosceles triangle, the degree of a base angle accounts for (1/6) of the sum of the interior angles. What is the apex angle of this isosceles triangle?
一个等腰三角形，一个底角的度数占内角和的(1/6)，这个等腰三角形的顶角是多少度？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">180 * (1/6)</gadget>
<output>30</output>

<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<gadget id="calculator">180 - 60</gadget>
<output>120</output>

<result>120</result>