Question 998071
The formula for perimeter is:
{{{ P = 2L + 2W }}}
given:
{{{ W = L/2 + 4 }}} 
{{{ L/2 = W - 4 }}}
{{{ L = 2W - 8 }}}
---------------
By substitution:
{{{ P = 2*( 2W - 8 ) + 2W }}}
{{{ P = 44 }}}
{{{ 44 = 2*( 2W - 8 ) + 2W }}}
{{{ 44 = 4W - 16 + 2W }}}
{{{ 6W = 60 }}}
{{{ W = 10 }}}
and
{{{ L = 2W - 8 }}}
{{{ L = 2*10 - 8 }}}
{{{ L = 12 }}}
The room is 12 m x 10 m
----------------------
check:
{{{ P = 2L + 2W }}}
{{{ P = 2*12 + 2*10 }}}
{{{ P = 24 + 20 }}}
{{{ P = 44 }}}
OK
{{{ W = L/2 + 4 }}} 
{{{ 10 = 12/2 + 4 }}} 
{{{ 10 = 6 + 4 }}}
{{{ 10 = 10 }}}
OK