Let the width of the rectangle be 'w' and the length be 'l'.
Before the changes, the area of the rectangle = w x l
After the changes, the length of the rectangle is increased by 12.5%, i.e. l' = 1.125l
The width of the rectangle is decreased by 10%, i.e. w' = 0.9w
Therefore, the area of the rectangle after the changes = w' x l'
= 0.9w x 1.125l
= 1.0125wl
Change in the area of the rectangle = (1.0125wl - wl) / wl
= 0.0125
Percentage change in the area of the rectangle = 0.0125 x 100
= 1.15 % Increase

Explanation:
• Area of a rectangle = Length x Width
• The length of the rectangle is increased by 12.5% and the width is decreased by 10%
• Therefore, the Area of the rectangle after the changes = 0.9w x 1.125l
• Change in the area of the rectangle = (1.0125wl - wl) / wl
• Percentage change in the area of the rectangle = 0.0125 x 100 = 1.15 % Increase

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