The sum of the top angles and one base angle of an isosceles triangle is 150°. what is its top angle
等腰三角形的顶角和一个底角的和是150°．它的顶角是多少°
<gadget id="calculator">180 - 150</gadget>
<output>30</output>

<gadget id="calculator">150 - 30</gadget>
<output>120</output>

<result>120</result>