Given:
Width of the rectangular yard = x feet
Length of the rectangular yard = x+4 feet
Perimeter of the rectangular yard is:
[tex]P=4x+8[/tex]
Perimeter of the yard = 84 feet
To find:
The length of the rectangular yard.
Solution:
Perimeter of the yard is 84 feet.
[tex]4x+8=84[/tex]
[tex]4x=84-8[/tex]
[tex]4x=76[/tex]
Divide both sides by 4.
[tex]x=\dfrac{76}{4}[/tex]
[tex]x=19[/tex]
So, the width of the rectangular yard is 19 feet.
Length = [tex]19+4[/tex]
Length = [tex]23[/tex]
The length of the rectangular field is 23 feet.
Therefore, the correct option is B.