Question 974468
The question would be, what is the width of the border of flowers?


ASSIGN VARIABLES
w and L, width and length of the garden before adding the surrounding flowers.
u, UNKNOWN width of the border of the flowers.
A, the area of the border of flowers surrounding the w & L part of the garden.


ANALYZE AND MAKE THE NEEDED EQUATION
{{{wL}}}, garden without the flower border
{{{(w+2u)(L+2u)}}}, whole area of combined flower border and unflowered garden
{{{highlight((w+2u)(L+2u)-wL=A)}}}, just the area of the border of flowers


The red-outlined equation has only the one unknown variable, u.  Simplify, solve for u, and then evaluate u according to:
A=92
w=7
L=12