The rectangle is 2.4m wide and 35dm long. The width of this rectangle was increased by 25% and the length was decreased by 20cm. How many square meters the area of this rectangle has decreased or increased.
1. Determine the width of the rectangle after the change. Since it was increased by 25%, it means that now it is 100 + 25 = 125%. We take the width as a and make up the proportion:
2.4 m – 100%, a – 125%;
2.4: a = 100: 125;
a = (2.4 x 125): 100;
a = 3m.
2. Determine the length of the rectangle after the change (we calculate in meters):
3.5 – 0.2 = 3.3 m;
3. Determine the initial area of the rectangle (we calculate in meters):
2.4 X 3.5 = 8.4 m²;
4. Determine the area of the rectangle after the change:
3 x 3.3 = 9.9 m²;
5. Determine how much the area of the rectangle has increased:
9.9 – 8.4 = 1.5 m².
Answer: the area of the rectangle has increased by 1.5 m².
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