Question 466352
the perimeter of rectangle is {{{P=2(L+W)}}}

given:

{{{P=102in}}}

{{{L=W+9in}}}

{{{2(L+W)=102in}}}

{{{2(L+W)/2=102in/2}}}

{{{L+W=51in}}}..replace {{{L}}} with {{{W+9in}}}

{{{W+9in+W=51in}}}

{{{2W=51in-9in}}}

{{{2W=42in}}}

{{{2W/2=42in/2}}}

{{{W=21in}}}

{{{L=W+9in}}}

{{{L=21in+9in}}}

{{{L=30in}}}