A rectangular piece of land, the ratio of length to width is 5:3, and the length is known to be 20 meters, what is the area of the land in square meters?
一块长方形的地，长和宽的比是5：3，已知长是20米，则这块地的面积为多少平方米．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(3/5) * 20</gadget>
<output>12</output>

<gadget id="calculator">20 * 12</gadget>
<output>240</output>

<result>240</result>