The perimeter of a rectangle is 42 feet. Find the dimensions if the length is fifteen feet shorter than three times the width (w). Choose the correct answer for the length.

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