fish tank problem A rectangular swimming pool with dimensions of 11m and 8m is built in a rectangular backyard. The area of the backyard is 1120m^2. If the strip of yard surrounding the pool is of uniform width, how wide is the strip?
So I tried to find a diagram but it doesn't seem to make sense because the backyard could have any dimensions...so i made the backyard 28 by 40 and then the answer would be 8.5 and 16 which isn't correct.
 A: The information that the strip of yard surrounding the pool is of uniform width is important. The following calculatins are done in meters.
See the picture below ($w$ denotes the width and $m$ is meters; please note that some of the $w$'s are rotated!):

Let a and b be the dimensions of the rectangular backyard. You know that $a\cdot b = 1120$.
As the strip of surrounding yard is of uniform width, you also know that
$a - 11 = b - 8$,
because $(a - 11 = 2w = b - 8)$. 
Now you can isolate a:
$a = b + 3$,
thus you must solve $(b+3)\cdot b = 1120$. The positive solution to this equation is $b=32$. Thus the width of the strip is $\frac{32-8}{2}$=12. Here I have just isolated $w$ in the equation $8 + 2w = b$, see the figure.
A: Let the width of the strip of yard around the pool be $w$ metres. Then the whole yard is a rectangle that is $11 + 2w$ metres long and $8 + 2w$ metres wide - you can see this because there's a strip of width $w$ on the left of the pool, and a strip of equal size on the right, and similarly for the top and bottom.
So what's the area of the yard + pool? How can you relate that to stuff you know?
