The measure of an apex angle of an isosceles triangle is (2/5) of its base angle. What is the measure of its apex angle?
一个等腰三角形的一个顶角的度数是它底角的(2/5)，它的顶角是多少度．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 + 1 + (2/5)</gadget>
<output>12/5 = around 2.4</output>

<gadget id="calculator">180 / (12/5)</gadget>
<output>75</output>

<gadget id="calculator">75 * (2/5)</gadget>
<output>30</output>

<result>30</result>