Question 344548
w=width
l=length
w=l-8
A=lw
A=20
{{{20=l(l-8)}}}
{{{20=l^2-8l}}}
{{{0=l^2-8l-20}}} 
you should see that +2 and -10 add to get -8 and multiply to get -20
{{{0=(l+2)(l-10)}}}
{{{l=10}}}
 the length cant be negative
{{{w=l-8}}}
{{{w=10-8}}}
{{{w=2}}}