Question 705606
Let {{{ z }}} = Zelma's age now
Let {{{ s }}} = her Son's age now
given:
(1) {{{ z = s + 18 }}}
(2) {{{ z - 1 = 3*( s - 1 ) }}}
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Substitute (1) into (2)
(2) {{{ s + 18 - 1 = 3*( s - 1 ) }}}
(2) {{{ s + 17 = 3s - 3 }}}
(2) {{{ 2s = 20 }}}
(2) {{{ s = 10 }}}
and, since
(1) {{{ z = s + 18 }}}
(1) {{{ z = 10 + 18 }}}
(1) {{{ z = 28 }}}
28 = Zelma's age now
10 = her Son's age now
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check:
(2) {{{ z - 1 = 3*( s - 1 ) }}}
(2) {{{ 28 - 1 = 3*( 10 - 1 ) }}}
(2) {{{ 27 = 3*9 }}}
(2) {{{ 27 = 27 }}}
OK