The perimeter of a rectangular vegetable field is 200 meters, and the ratio of length to width is 7:3. What is the area of this vegetable field?
一个长方形的菜地的周长是200米，长和宽的比是7：3，这块菜地的面积是多少？
<gadget id="calculator">200 / 2</gadget>
<output>100</output>

<gadget id="calculator">3 + 7</gadget>
<output>10</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">100 * (7/10)</gadget>
<output>70</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">100 * (3/10)</gadget>
<output>30</output>

<gadget id="calculator">70 * 30</gadget>
<output>2_100</output>

<result>2_100</result>