One side of the rectangle was reduced by 20%, and then both sides were enlarged by 20%.
June 16, 2021 | education
| One side of the rectangle was reduced by 20%, and then both sides were enlarged by 20%. It turned out that the perimeter did not change. How many times is the rectangle longer than its width?
Suppose the sides of the rectangle were equal to x and y.
When x was reduced by 20%, it turned out:
x * (100 – 20): 100 = 0.8 * x.
Then both sides increased by 20%.
One side turned out:
y * (100 + 20): 100 = 1.2 * y.
the second side turned out:
0.8 * x * (100 + 20): 100 = 0.8 * x * 1.02 = 0.96 * x.
Originally, the perimeter of the rectangle was:
2 * (x + y).
After changing the sides, the perimeter became equal to:
2 * (0.96 * x + 1.2 * y).
We get:
2 * (x + y) = 2 * (0.96 * x + 1.2 * y),
x + y = 0.96 * x + 1.2 * y,
0.04 * x = 0.2 * y,
x = 5 * y.
Answer: 5 times.
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