Question 488641
let {{{a}}} = length
Let {{{b}}} = width
given:
(1) {{{ a = 3b }}}
(2) {{{ 2a + 2b = 56 }}}
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Substitute (1) into (2)
(2) {{{ 2*(3b) + 2b = 56 }}}
(2) {{{ 6b + 2b = 56 }}}
(2) {{{ 8b = 56 }}}
(2) {{{ b = 7 }}}
and, since
(1) {{{ a = 3b }}}
(1) {{{ a = 3*7 }}}
(1) {{{ a = 21 }}}
The dimensions are 7 x 21