Question 1150389
Let {{{ a }}} = my father's age now
Let {{{ b }}} = my age now
(1) {{{ a - 12 = 2*( b - 12 ) }}}
(2) {{{ ( a - 3 ) + ( b - 3 ) = 108 }}}
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(1) {{{ a - 12 = 2b - 24 }}}
(1) {{{ -a + 2b = 12 }}}
and
(2) {{{ a + b - 6 = 108 }}}
(2) {{{ a + b = 114 }}}
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add (1) and (2)
(1) {{{ -a + 2b = 12 }}}
(2) {{{ a + b = 114 }}}
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{{{ 3b = 126 }}}
{{{ b = 42 }}}
and
(2) {{{ a + 42 = 114 }}}
(2) {{{ a = 72 }}}
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My father is 72 now
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check:
(1) {{{ a - 12 = 2*( b - 12 ) }}}
(1) {{{ 72 - 12 = 2*( 42 - 12 ) }}}
(1) {{{ 60 = 2*30 }}}
(1) {{{ 60 = 60 }}}
and
(2) {{{ ( a - 3 ) + ( b - 3 ) = 108 }}}
(2) {{{ ( 72 - 3 ) + ( 42 - 3 ) = 108 }}}
(2) {{{ 69 + 39 = 108 }}}
(2) {{{ 108 = 108 }}}
OK