The perimeter of the rectangle ABCD is 40 dm. The length of the rectangle is 12cm. Find the width of the rectangle.

The perimeter P of the rectangle ABCD is 40 decimeters.
The length a of the quadrangle is 12 centimeters.
The perimeter is the sum of the lengths of all sides of the shape.
Two lengths are equal to each other and two widths are also equal to each other.
It follows that the width of this figure is calculated by the formula b = (P – a – a): 2.
Let’s convert decimeters to centimeters:
1 dm = 10 cm;
40 dm = 400 cm.
Let’s calculate the width of the rectangle:
b = (P – a – a): 2 = (400 – 12 – 12): 2 = 188 cm.
Answer: The width of the rectangle is 188 cm.

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