A piece of right-angled triangle land has a perimeter of 36 meters and the ratio of the lengths of the three sides is 3:4:5. What is the area of the land in square meters?
一块直角三角形地，周长36米，三条边长之比是3：4：5，这块地的面积是多少平方米．
<gadget id="calculator">3 + 4 + 5</gadget>
<output>12</output>

<gadget id="calculator">4 / 12</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">36 * (1/3)</gadget>
<output>12</output>

<gadget id="calculator">3 / 12</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">36 * (1/4)</gadget>
<output>9</output>

<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">12 * (9/2)</gadget>
<output>54</output>

<result>54</result>