The perimeter of the rectangle is 128 m, and its length is 57 m. Calculate the area of this rectangle.

It is known that the area of ​​a rectangle (S) is determined by the formula: S = a * b, where a is the length of the rectangle, b is the width of the rectangle.
This means that in order to calculate the area of ​​a rectangle, you need to know its length and width. By the problem statement, only the length is known. We need to calculate the width of the rectangle.
It is known that the perimeter of a rectangle (P) is equal to the sum of the lengths of all its sides: P = a + b + a + b = 2a + 2b.
If you know the perimeter and length of the rectangle, you can calculate its width using the formula:
b = (P – 2a): 2.
Let’s calculate the width of the given rectangle:
b = (128 – 2 * 57): 2,
b = (128 – 114): 2,
b = 14: 2,
b = 7.
This means that the width of the rectangle is b = 7 cm.
Now let’s calculate the area of ​​the given rectangle:
S = 57 * 7 = 399 cm2.
Answer: 399 cm2.