Question 1053592
Let {{{ a }}} = Fred's age now
Let {{{ b }}} = John's age now
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(1) {{{ a = b - 10 }}}
(2) {{{ a - 2 = (1/2)*( b - 2 ) }}}
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Substitute (1) into (2)
(2) {{{ b - 10 - 2 = (1/2)*( b - 2 ) }}}
(2) {{{ b - 12 = (1/2)*( b - 2 ) }}}
(2) {{{ 2*( b - 12 ) = b - 2 }}}
(2) {{{ 2b - 24 = b - 2 }}}
(2) {{{ b = 24 - 2 }}}
(2) {{{ b = 22 }}}
and
(1) {{{ a = b - 10 }}}
(1) {{{ a = 22 - 10 }}}
(1) {{{ a = 12 }}}
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Fred is 12
John is 22
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check:
(2) {{{ a - 2 = (1/2)*( b - 2 ) }}}
(2) {{{ 12 - 2 = (1/2)*( 22 - 2 ) }}}
(2) {{{ 10 = (1/2)*20 }}}
92) {{{ 10 = 10 }}}
OK