Answer:
Length: 110 feet
Width: 50 feet
Step-by-step explanation:
we know that
The perimeter of rectangle is equal to
[tex]P=2(L+W)[/tex]
where
L is the length of rectangle
W is the width of rectangle
we have
[tex]P=320\ ft[/tex]
so
[tex]320=2(L+W)[/tex] ----> equation A
[tex]L=3W-40[/tex] ----> equation B
Solve the system by substitution
substitute equation B in equation A
[tex]320=2(3W-40+W)[/tex]
solve for W
[tex]320=2(4W-40)[/tex]
[tex]320=8W-80[/tex]
[tex]8W=320+80[/tex]
[tex]8W=400[/tex]
[tex]W=50\ ft[/tex]
Find the value of L
[tex]L=3(50)-40=110\ ft[/tex]
therefore
The dimensions of the field are
Length: 110 feet
Width: 50 feet