The perimeter of a rectangle is 42cm, the ratio of its length to width is 4:3, what is its area in cm**2.
一个长方形的周长是42cm，它的长与宽的比是4：3，它的面积是多少cm**2．
<gadget id="calculator">42 / 2</gadget>
<output>21</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">21 * (4/7)</gadget>
<output>12</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">21 * (3/7)</gadget>
<output>9</output>

<gadget id="calculator">12 * 9</gadget>
<output>108</output>

<result>108</result>