Question 61038
{{{L=3W}}}
{{{P=72}}}
The perimeter of a rectangle, P, = {{{2W+2L}}}.
So, {{{2W+2L=72}}}. Replace L with 3W and you get
{{{2W+2*3W=72}}}
Or {{{2W+6W=72}}}
Or {{{8W=72}}}
So, {{{W=9}}}
The length, L, is 3 times the width so {{{L=27}}}.

Verification:

{{{2W+2L=72}}}. {{{2*9+2*27 = 18+54 = 72}}}.