Question 691607
Let {{{ a }}} = her age now
Let {{{ b }}} = her Son's age now
{{{ a-1 }}} = her age 1 year ago
{{{ b-1 }}} = her Son's age 1 year ago
given:
(1) {{{ a = b + 18 }}}
(2) {{{ a - 1 = 3*( b - 1 ) }}}
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Substitute (1) into (2)
(2) {{{ b + 18 - 1 = 3*( b - 1 ) }}}
(2) {{{ b + 17 = 3b - 3 }}}
(2) {{{ 2b = 20 }}}
(2) {{{ b = 10 }}}
and, since
(1) {{{ a = b + 18 }}}
(1) {{{ a = 10 + 18 }}}
(1) {{{ a = 28 }}}
Zelma is 28
Her Son is 10
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check:
(2) {{{ a - 1 = 3*( b - 1 ) }}}
(2) {{{ 28 - 1 = 3*( 10 - 1 ) }}}
(2) {{{ 27 = 3*9 }}}
(2) {{{ 27 = 27 }}}
OK