Jiangtan Park used to have a rectangular lawn with a length of 50 meters and a width of 40 meters. Now the length of the lawn has increased by 40 meters and its width by 10 meters. How many square meters has the area of the rectangular lawn increased?
江滩公园原来有一块长方形草坪，长50米，宽40米，现在这块草坪的长增加了40米，宽增加了10米．这块长方形草坪的面积增加了多少平方米？
<gadget id="calculator">50 + 40</gadget>
<output>90</output>

<gadget id="calculator">40 + 10</gadget>
<output>50</output>

<gadget id="calculator">90 * 50</gadget>
<output>4_500</output>

<gadget id="calculator">50 * 40</gadget>
<output>2_000</output>

<gadget id="calculator">4_500 - 2_000</gadget>
<output>2_500</output>

<result>2_500</result>