In an isosceles triangle, the measure ratio of the top angle to the base angle is 5:2, what is the base angle?
在等腰三角形中，顶角与底角的度数比是5：2，底角是多少．
<gadget id="calculator">5 + 2 + 2</gadget>
<output>9</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">180 * (2/9)</gadget>
<output>40</output>

<result>40</result>