A rectangular lawn, if the width remains the same, the length increases by 5 meters, the area increases by 40 square meters; if the length remains the same, the width increases by 2 meters, the area increases by 50 square meters. What is the area of the lawn in square meters?
一块长方形的草坪，如果宽不变，长增加5米，面积就增加40平方米；如果长不变，宽增加2米，面积就增加50平方米．这块草坪的面积是多少平方米．
<gadget id="calculator">50 / 2</gadget>
<output>25</output>

<gadget id="calculator">40 / 5</gadget>
<output>8</output>

<gadget id="calculator">25 * 8</gadget>
<output>200</output>

<result>200</result>