The ratio of a base angle to a top angle of an isosceles triangle is 1:4, what is the apex angle in degrees?
一个等腰三角形的一个底角与项角的度数比是1：4，它的顶角是多少度．
<gadget id="calculator">1 + 1 + 4</gadget>
<output>6</output>

<gadget id="calculator">180 / 6</gadget>
<output>30</output>

<gadget id="calculator">30 * 4</gadget>
<output>120</output>

<result>120</result>