A rectangle, the ratio of length to width is 7:5, given that the perimeter of this rectangle is 168 cm, find the area of this rectangle.
一个长方形，长与宽的比是7：5，已知这个长方形的周长是168厘米，求这个长方形的面积．
<gadget id="calculator">168 / 2</gadget>
<output>84</output>

<gadget id="calculator">7 + 5</gadget>
<output>12</output>

<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">84 * (7/12)</gadget>
<output>49</output>

<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">84 * (5/12)</gadget>
<output>35</output>

<gadget id="calculator">49 * 35</gadget>
<output>1_715</output>

<result>1_715</result>