Question 1026666
Let {{{ j }}} = Jill's age now
Let {{{ b }}} = Brian's age now
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(1) {{{ j = b - 10 }}}
(2) {{{ j + 5 = ( 2/3 )*( b + 5 ) }}}
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Multiply both sides of (2) by {{{ 3 }}}
(2) {{{ 3*( j + 5 ) = 2*( b + 5 ) }}}
(2) {{{ 3j + 15 = 2b + 10 }}}
(2) {{{ 2b - 3j = 5 }}}
and
(1) {{{ b - j = 10 }}}
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Multiply both sides of (1) by {{{ 2 }}}
and subtract (2) from (1)
(1) {{{ 2b - 2j = 20 }}}
(2) {{{ -2b + 3j = -5 }}}
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{{{ j = 15 }}}
and
(1) {{{ j = b - 10 }}}
(1) {{{15 = b - 10 }}}
(1) {{{ b = 25 }}}
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{{{ j + 7 = 15 + 7 }}}
{{{ j + 7 = 22 }}}
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In 7 yrs, Jill will be 22
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check answer:
(2) {{{ j + 5 = ( 2/3 )*( b + 5 ) }}}
(2) {{{ 15 + 5 = ( 2/3 )*( 25 + 5 ) }}}
(2) {{{ 20 = (2/3)*30 }}}
(2) {{{ 60 = 2*30 }}}
(2) {{{ 60 = 60 }}}
and
(1) {{{ j = b - 10 }}}
(1) {{{15 = 25 - 10 }}}
(1) {{{ 15 = 15 }}}
OK