A base angle of an isosceles triangle is (2/5) of the top angle. How many degrees is the top angle?
等腰三角形的一个底角度数为顶角的(2/5)，这个顶角是多少度．
<gadget id="calculator">2 + 2 + 5</gadget>
<output>9</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">180 * (5/9)</gadget>
<output>100</output>

<result>100</result>