Opposite sides of a rectangle are congruent.
Use the given information to set up an equation and solve for the perimeter.
For the equation, use the sum of the sides, or use two times length plus two times width.

Perimeter	=	length	+	length	+	width	+	width
	=	25 feet	+	25 feet	+	15 feet	+	15 feet
	=	80 feet

Perimeter	=	(2 × length)	+	(2 × width)
	=	(2 × 25 feet)	+	(2 × 15 feet)
	=	50 feet	+	30 feet
	=	80 feet

The perimeter of the rectangle is 80 feet.

Use the given information to set up an equation and solve for the width.
For the equation, use the sum of the sides, or use two times length plus two times width.

Perimeter	=	length	+	length	+	width	+	width
60 feet	=	20 feet	+	20 feet	+	width	+	width
60 feet	=	40 feet	+	width	+	width
60 feet	=	40 feet	+	10 feet	+	10 feet

Perimeter	=	(2 × length)	+	(2 × width)
60 feet	=	(2 × 20 feet)	+	(2 × width)
60 feet	=	40 feet	+	(2 × width)
60 feet	=	40 feet	+	20 feet
60 feet	=	40 feet	+	(2 × 10 feet)

The width of the rectangle is 10 feet.

Use the formula for the area of a rectangle.

Area	=	length × width
	=	10 feet × 4 feet
	=	40 square feet

The area of the rectangle is 40 square feet.

Use the given information to set up an equation and solve for the width.

	Area	=	length × width
9 times some number equals 45	45 sq ft	=	9 ft × width
related division: 45 ÷ 9 = 5	45 sq ft	=	9 ft × 5 ft

So, the width of the rectangle is 5 feet.