If the perimeter of a parallelogram is 30 centimeters and the heights of two adjacent sides are 2 centimeters and 3 centimeters respectively, what is its area in square centimetres?
一个平行四边形的周长是30厘米，相邻两条边上的高分别是2厘米和3厘米，它的面积是多少平方厘米．
<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) * 6</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<result>18</result>