The circumference of a rectangle is 40 cm. Its length and width are cm. The book is a prime number and a composite number respectively. The largest area of this rectangle is () square cm

The circumference of a rectangle is 40 cm. Its length and width are cm. The book is a prime number and a composite number respectively. The largest area of this rectangle is () square cm

The sum of length and width is
40 △ 2 = 20 cm
20＝2＋18＝5＋15＝9＋11
The biggest is
9 × 11 = 99 square centimeter

For a square, its length and width are increased by 3 meters, and its area is increased by 51 square meters. What is the perimeter of the original rectangle?

Square side length: [(51-3 * 3) / 2] / 3 = 7M
Perimeter: 4 * 7 = 28m

The perimeter of a rectangle is 180cm, and the ratio of length to width is 3:2. What is the area of the rectangle in square centimeter

Half of the circumference is equal to the sum of length and width
Then, 180 / 2 = 90
Let the length be 3x and the width be 2x. So 3x + 2x = 5x = 180
The solution is x = 36
So length = 3 * 36 = 108, width = 72
Area = 108 * 72 = 7776
Pay attention to the unit
Please use

Given a rectangle, the ratio of length to width is 5:4, and its area is 720, what is the perimeter of the rectangle?
No equations

The ratio of length to width is 5:4, and the ratio of rectangular area to square area with the same length and width is also 5:4
Square area = 720 × 4 / 5 = 576
Square side length = 24
Rectangle width = square side length = 24
Length of rectangle = 24 × (5 / 4) = 30
Perimeter of rectangle = 2 × (24 + 30) = 108