Question 329404
let width of rectangle be x
length will be 2x+70
Area of rectangle = length * width
=x(2x+70)
..
Area of square = L^2
L= 30
area = 30^2= 900
..
But the area of square = area of rectangle
x(2x+70)=900
2x^2+70x=900
divide by 2
x^2+35x=450
x^2+35x-450=0
x^2+45x-10x-450=0
x(x+45)-10(x+45)=0
(x+45)(x-10)=0
x=-45 OR x=10
ignore the negative value
width = 10 
Length = 2x +70
= 2*10+70= 90 feet length
CHECK
AREA = 90*10 =900 square feet