Question 249878
Area = (length)(width)

A=84 sq. ft.
84=(w+5)(w)
84=w^2+5w  [multiply terms]
84-84=w^2+5w-84  [move all of the terms to one side of the equation]
0=w^2+5w-84
(x+12)(x-7)=0[Factor]
.
x+12=0 [set each factor equal to zero]
x=-12 [solve for "x"]
.
x-7=0
x=7
.
Solutions:  x= -12,7