The perimeter of the rectangle is 60cm, the ratio of length to width is 7:3, what is the area?
长方形的周长是60cm，长宽比是7：3，面积是多少．
<gadget id="calculator">60 / 2</gadget>
<output>30</output>

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

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

<gadget id="calculator">30 * (7/10)</gadget>
<output>21</output>

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

<gadget id="calculator">30 * (3/10)</gadget>
<output>9</output>

<gadget id="calculator">21 * 9</gadget>
<output>189</output>

<result>189</result>