Step-by-step explanation:
perimeter is 2 times length plus 2 times width
let the length be x and the width be y
then x-3y=1, so x=3y+1
plug this into the perimeter formula
2x+2y=2(3y+1)+2y=6y+2+2y=8y+2
we know this equals 42, so set them equal and solve for y
8y+2=42
8y=40
y=5
solve for x
x=3y+1=3(5)+1=16
the rectangle is 5 ft by 16 ft
