Question 417960
assume,  width = x inches

==> length =  3x + 7

perimeter p 86 inches


==> {{{ 86 = 2( 3x+7 + x)}}}

==> {{{ 86/2 = 2( 3x+7 + x)/2}}}

==> {{{ 43 =  3x+7 + x }}}

==> {{{ 43 = 4x+7}}}

==> {{{ 43-7 = 4x+7-7}}}

==> {{{ 36 = 4x }}}

==> {{{ 36/4 = 4x/4 }}}

==> {{{ 9 = x }}}

==> width = 9 inches

==> length = 3(9) + 7 = 34 inches