The perimeter of an equilateral triangle is 54 decimeters and the height is 15.6 decimeters. What is its area?
一个等边三角形的周长是54分米，高是15.6分米，它的面积是多少平方分米？
<gadget id="calculator">54 / 3</gadget>
<output>18</output>

<gadget id="calculator">15.6 / 2</gadget>
<output>7.8</output>

<gadget id="calculator">18 * 7.8</gadget>
<output>140.4</output>

<result>140.4</result>