There is an elongated lawn with a perimeter of 80 meters. After re-trimming, the length is shortened by 5 meters and the width is increased by 5 meters. The resulting area is 75 square meters larger than the original one. Find the area of the lawn after trimming.
有一块长放形草坪，周长80米，经过重新修整后，长缩短了5米，宽增加了5米，结果面积比原来增加了75平方米，求修整后草坪面积是多少．
<gadget id="calculator">80 / 2</gadget>
<output>40</output>

<gadget id="calculator">40 * 5</gadget>
<output>200</output>

<gadget id="calculator">5 * 5</gadget>
<output>25</output>

<gadget id="calculator">200 + 25 + 75</gadget>
<output>300</output>

<gadget id="calculator">1 - 1 - 40</gadget>
<output>-40</output>

<gadget id="calculator">40 + 5 + 5 + (-40)</gadget>
<output>10</output>

<gadget id="calculator">300 / 10</gadget>
<output>30</output>

<gadget id="calculator">40 - 30</gadget>
<output>10</output>

<gadget id="calculator">30 * 10</gadget>
<output>300</output>

<gadget id="calculator">300 + 75</gadget>
<output>375</output>

<result>375</result>