Question 77607
If we let L=length, w=width we get


{{{L-6=w}}} and the perimeter equals 

{{{P=2L+2w}}}


{{{68=2L+2(L-6)}}} Plug in L-6 into w and let P=68


{{{68=2L+2L-12}}} Distribute


{{{68=4L-12}}} Combine like terms



{{{80=4L}}} Add 12 to both sides


{{{80/4=L}}} Divide both sides by 4


{{{L=20}}} So this is the length

Use this to find the width:

{{{20-6=w}}}

{{{w=14}}}

So the dimensions are width=14, length=20

Check:

{{{68=2(20)+2(14)}}} plug in L=20, w=14, P=68

{{{68=40+28}}}

{{{68=68}}} works