Question 315227
For a rectangle,
{{{P=2*(L+W)=108}}}
{{{L+W=54}}}
{{{L+(L-12)=54}}}
{{{2L-12=54}}}
{{{2L=66}}}
{{{highlight(L=33)}}}
{{{W=L-12=33-12}}}
{{{highlight(W=21)}}}