Use 84 cm wire to form a right triangle, the ratio of the length of this triangle is 3:4:5. What is the area of this triangle?
用84厘米的铁丝围成一个直角三角形，这个三角形长度的比是3：4：5．这个三角形的面积是多少？
<gadget id="calculator">3 + 4 + 5</gadget>
<output>12</output>

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

<gadget id="calculator">84 * (1/4)</gadget>
<output>21</output>

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

<gadget id="calculator">84 * (1/3)</gadget>
<output>28</output>

<gadget id="calculator">28 / 2</gadget>
<output>14</output>

<gadget id="calculator">21 * 14</gadget>
<output>294</output>

<result>294</result>