A rectangular vegetable field has a measured circumference of 42 meters and a ratio of length to width of 5:2. What is the area of this vegetable field in square meters?
一块长方形菜地，测得周长是42米，长和宽的比是5：2．这地菜地的面积是多少平方米？
<gadget id="calculator">5 + 2</gadget>
<output>7</output>

<gadget id="calculator">42 / 2 / 7</gadget>
<output>3</output>

<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

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

<result>90</result>