Lili ran 3 laps around the school's rectangular playground, a total of 1440 meters. It is known that the difference between the length and width of this rectangular playground is 60 meters, so what is the area of the playground in square meters?
丽丽沿着学校长方形操场四周跑了3圈，共跑了1440米．已知这个长方形操场的长宽相差60米，那么操场的面积是多少平方米．
<gadget id="calculator">60 + 240</gadget>
<output>300</output>

<gadget id="calculator">300 / 2</gadget>
<output>150</output>

<gadget id="calculator">150 - 60</gadget>
<output>90</output>

<gadget id="calculator">150 * 90</gadget>
<output>13_500</output>

<result>13_500</result>