Question 978889
x, width
y, length
u, uniform width of the walk path around the rectangular garden
A, the area of the walk path around the garden
-
u is unknown
y=30
x=40
A=280


Garden area, {{{xy}}}
Combined walkway and garden area, {{{(x+2u)(y+2u)}}}
Walkway area only, {{{highlight_green((x+2u)(y+2u)-xy=A)}}}


"Find the width of the walk."
The only unknown variable in the green-outlined equation is u.  That is what the question
asks to find.  Work with THAT equation to solve for u.  Try to go as far as possible completely
in symbols before subsituting the given values.



---partway through the process,
{{{2uy+2xu+4u^2-A=0}}}
{{{4u^2+(2x+2y)u-A=0}}}