Question 109136
if the {{{length }}}of a rectangle is {{{3}}} {{{inches}}}{{{ longer}}} than the {{{width}}}, then we have

{{{L = W + 3in}}}.....=> {{{W= L - 3}}}

 if the {{{perimeter = P}}} of the rectangle is {{{78}}}, then we have:

{{{P = 2(L+W)}}}

{{{78 = 2 ( L + (L - 3))}}}

{{{78 = 2(2L - 3)}}}

{{{78 = 4L - 6}}}

{{{4L = 78 + 6}}}

{{{4L = 84}}},,,,,,,divide both sides by {{{4}}}

{{{L = 21}}}

then:

{{{W = 21 - 3}}}

{{{W = 18}}}

check:

{{{2(21 + 18) = 2* 39 = 78}}}