An isosceles triangle has a vertex angle to a base angle whose measure ratio is 4:1, what is its vertex angle in degree?
一个等腰三角形的顶角与一个底角的度数比是4：1，那么它的顶角是多少度．
<gadget id="calculator">4 + 1 + 1</gadget>
<output>6</output>

<gadget id="calculator">4 / 6</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">180 * (2/3)</gadget>
<output>120</output>

<result>120</result>