Question 250419
{{{ A=L*W=20 }}}
{{{ W=L-8}}}
{{{ L*(L-8)=20}}}
{{{ L^2-8L=20}}}
{{{ L^2-8L-20=0}}}
Factor
{{{ (L-10)(L+2)=0}}}
Keep only the positive solution.
{{{ L-10=0}}}
{{{ L=10}}}
{{{ W=L-8}}}
{{{ W=2}}}