A rectangular swimming pool originally had a length of 75 meters and a width of 50 meters. After expansion, the length is increased by 25 meters and the width is increased to 80 meters. How much larger is the area of the swimming pool after the expansion?
一个长方形游泳池原来的长是75米，宽50米，扩建后长增加25米，宽增加为80米，这个游泳池扩建后的面积比原来大多少？
<gadget id="calculator">75 + 25</gadget>
<output>100</output>

<gadget id="calculator">100 * 80</gadget>
<output>8_000</output>

<gadget id="calculator">75 * 50</gadget>
<output>3_750</output>

<gadget id="calculator">8_000 - 3_750</gadget>
<output>4_250</output>

<result>4_250</result>