You can put this solution on YOUR website!
Let's find the equation for the area of the poster + frame.
The area of the poster alone is:
but the total size with the frame is 4 inches more on each side, so the area then becomes:
and since the length, L = W+4, you can substiute this to get:
and the total area is given as 672 sq.in, so...
Simplifying this, you get:
Now subtract 672 from both sides.
Now that we have the quadratic equation, we can factor it, if possible:
This does not match exactly any of the given possible answers, does it?