Question 696143
Let {{{ L }}} = length of rectangle



"rectangle's width is one third its length"
width = {{{ L/3 }}}



"its perimeter is 80 meters" : perimeter = 2*(length + width)
{{{ 2(L + L/3) = 80 }}}
{{{ L + L/3 = 40 }}}
{{{ 3L/3 + L/3 = 40 }}}
{{{ 4L/3 = 40 }}}
{{{ 4L = 120 }}}
{{{ L = 30 }}}



"What is the dimensions of the rectangle?"
Length = {{{ L = 30 }}}
Width = {{{ L/3 = 30/3 = 10 }}}


So, It is 30 x 10