Question 547732
Let l be the length, and w be the width.  From the question we know: 
{{{w+4=l}}}     (1)
and 
{{{2w+2l=80}}}    (2)

Substituting (1) into (2) we get:
{{{2w+2(w+4)=80}}}
{{{2w+2w+8=80}}}
{{{4w=80-8}}}
{{{4w=72}}}
{{{w=72/4}}}
{{{w=18}}}

Substituting this value of w into (1) we get that {{{l=18+4=22}}}


Now, the formula for area is as follows:
{{{A=lw}}}
{{{A=22*18}}}
{{{A=396}}}

Therefore the area is 396 metres squared.  


Hopefully this helps!  Just let me know if you are still unsure