In an isosceles triangle, the measure ratio of the vertex angle to a base angle is 4:3, what is the vertex angle?
等腰三角形中，顶角与一个底角的度数比是4：3，顶角是多少度．
<gadget id="calculator">4 + 3 + 3</gadget>
<output>10</output>

<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">180 * (2/5)</gadget>
<output>72</output>

<result>72</result>