Question 77025
if we let x=width, y=length we get

{{{480=x*y}}}

where the length is 

{{{y=2x-16}}}

{{{480=x*(2x-16)}}} Substitute 2x-16 into y

{{{480=2x^2-16x}}} Distribute

{{{0=2x^2-16x-480}}} Subtract 480 from both sides

Now we use the quadratic formula to solve for x:

*[invoke quadratic "x", 2, -16, -480 ]

Since a negative width doesn't make any sense, our answer is 20. So our length is

{{{y=2(20)-16}}}
{{{y=40-16}}}
{{{y=24}}}

So our width is 20 and our length is 24.