The ratio of length to width of a rectangle is 4:3, and its perimeter is 840 cm. What is its area in square centimeters?
一个长方形的长与宽之比是4：3，周长是840厘米，它的面积是多少平方厘米．
<gadget id="calculator">840 / 2</gadget>
<output>420</output>

<gadget id="calculator">4 + 3</gadget>
<output>7</output>

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

<gadget id="calculator">420 * (4/7)</gadget>
<output>240</output>

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

<gadget id="calculator">420 * (3/7)</gadget>
<output>180</output>

<gadget id="calculator">240 * 180</gadget>
<output>43_200</output>

<result>43_200</result>