The perimeter of the rectangle is 8dm 4 cm. The length of this rectangle is 3dm. Find the area of this rectangle and what is the width?

Determine the width of the rectangle by expressing it from the formula for calculating the perimeter:
P = 2a + 2b.
b = (P – 2a): 2. Provided that the sum of all sides = 8 dm 4 cm (8.4 dm), and the length is 3 dm:
b = (8.4 – 2 * 3): 2 = 2.4: 2 = 1.2 dm.
Let’s find the area of such a figure:
S = a * b = 3 * 1.2 = 3.6 dm².