The perimeter of the rectangle = 2(length + width)
From the given figure
The length of the rectangle = 3x
The width of the rectangle = x
The perimeter = 2(3x + x)
Since the perimeter of the rectangle P = 1000
We will equate the expression of the perimeter above by 1000
2(3x + x) = 1000
Let us simplify the left side
2(3x) + 2(x) = 1000
6x + 2x = 1000
Add the like terms
8x = 1000
Divide both sides by 8
x = 125
To find the length
Substitute x by 125
The length = 3(125) = 375
Equation is 2(3x + x) = 1000
Length = 375
