<PRE><B>Question 663506</B>
let x= length
    y = width  = x - 5

A= Area of Rectangle

Formula:  Area of Rectangle = length x width

84 = (x)(x - 5)
84 = x2 - 5x

Transpose 84 to the other side and get:
x2 -5x-84 = 0

Factor or by using quadratic formula, and get:
(x-7) = 0  (x-12) = 0: Both gives correct answer but we will use x-12: 

Therefore;
x = 12
and y = x-5 = 7

Checking:

Area = length x width
     = (12 feet)(7 feet)
     = 84 square feet






 



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