Answer:
280 feet
Step-by-step explanation:
Let width of rectangle be x
Since we are given that the length of the rectangle is three times the width.
⇒ Length = 3x
Now, perimeter of rectangle = [tex]2(Length+Width)[/tex]
Perimeter of rectangular area:
[tex] 320 =2(x+ 3x)[/tex]
[tex] 320 =2(4x)[/tex]
[tex] 320 =8x[/tex]
[tex] \frac{320}{8} = x[/tex]
[tex]40= x[/tex]
Thus the width of the rectangular area is 40 feet .
Length = 3x= 40*3=120 feet.
Since we are given that The barn forms one end of the rectangle
⇒[tex](2\times length)+width[/tex]
⇒[tex](2\times 120)+40[/tex]
⇒[tex]240+40[/tex]
⇒[tex]280[/tex]
Hence he must buy 280 feet of fence to form barn if the perimeter of the rectangle is 320 feet
