Question 877998
Let width = w
Let length = 2w+5

{{{w(2w+5)=12}}}
{{{2w^2+5w=12}}}
{{{2w^2+5w-12=0}}}
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
{{{w = (-5 +- sqrt( 5^2-4*2*-12 ))/(2*2) }}}
{{{w = (-5 +- sqrt( 25-4*2*-12 ))/(2*2) }}}
{{{w=(-5+-sqrt(121))/4}}}
Because both sides must be positive, ignore the negative answer.
{{{w=(-5+11)/4}}}
{{{w=6/4}}}
{{{w=1.5}}}
The width is 1.5 and the length is 8.