Question 1054924
Let {{{ a }}} = Brian's age now
Let {{{ b }}} = his daughter's age now
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(1) {{{ a = 2b + 19 }}}
(2) {{{ a + 5 = 3*( b + 5 ) }}}
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(2) {{{ a + 5 = 3b + 15 }}}
(2) {{{ a - 3b = 10 }}}
and
(1) {{{ a - 2b = 19 }}}
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Subtract (2) from (1)
(1) {{{ a - 2b = 19 }}}
(2) {{{ -a + 3b = -10 }}}
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{{{ b = 9 }}}
and
(1) {{{ a = 2b + 19 }}}
(1) {{{ a = 2*9 + 19 }}}
(1) {{{ a = 18 + 19 }}}
(1) {{{ a = 37 }}}
Brian is 37 
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check:
(2) {{{ a + 5 = 3*( b + 5 ) }}}
(2) {{{ 37 + 5 = 3*( 9 + 5 ) }}}
(2) {{{ 42 = 3*14 }}}
(2) {{{ 42 = 42 }}}
OK