The perimeter of a rectangle is 42cm, and the ratio of length to width is 5:2. What is the area of the rectangle in cm**2.
一个长方形的周长是42cm，长与宽的比是5：2，这个长方形的面积是多少cm**2．
<gadget id="calculator">42 / 2</gadget>
<output>21</output>

<gadget id="calculator">5 + 2</gadget>
<output>7</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">21 * (5/7)</gadget>
<output>15</output>

<gadget id="calculator">21 - 15</gadget>
<output>6</output>

<gadget id="calculator">15 * 6</gadget>
<output>90</output>

<result>90</result>