Question 878505
The first step is to write equations for length and width.
Length is 1 less than 3 times width or length is 3 times width minus 1.

{{{L=3W-1}}}
{{{L}}} is length and {{{W}}} is width.
Width on the other hand is simply {{{W=W}}}.


Now the equation for the perimeter is {{{P=2L + 2W}}} or {{{P= L+L+W+W}}}. The first option is simpler.


Plug in {{{3W-1}}} for {{{L}}} then solve for {{{W}}}.


{{{30= 2(3W-1)+2W}}}
{{{30=6W-2+2W}}}
{{{32=8W}}}
{{{W=4}}}


We are looking for length so we plug 4 back into length's equation.
{{{L=3W-1}}}
{{{L=3(4)-1}}}
{{{L=11}}}


Check answer.
{{{30=2(11)+2(4)}}}
{{{30=30}}}


The length is 11.