Question 802309
For convenience let's call the given side the length, so...
{{{l=2x+4 }}}

W are also given the perimeter...6x+4 and we for a rectangle, {{{P=2(l+w) }}}
therefore:

{{{2(l+w)=6x+4 }}}
so we have enough information to solve for w: 

{{{2x+4+w=3x+2}}}
{{{w=x-2}}} 

Now we have enough information to solve for area.
{{{A=l*w}}}
so
{{{A=(2x+4)(x-2)=
2x^2-8 cm^2}}}