Question 698270
Let {{{ a }}} = John's age now
Let {{{ b }}} = his Brother's age now
given:
(1) {{{ a = b + 6 }}}
(2) {{{ a + 4 = 2*( b + 4 ) }}}
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Substitute (1) into (2)
(2) {{{ b + 6 + 4 = 2*( b + 4 ) }}}
(2) {{{ b + 10 = 2b + 8 }}}
(2) {{{ b = 10 - 8 }}}
(2) {{{ b = 2 }}}
and
(1) {{{ a = b + 6 }}}
(1) {{{ a = 2 + 6 }}}
(1) {{{ a = 8 }}}
John is 8 yrs old
check:
(2) {{{ a + 4 = 2*( b + 4 ) }}}
(2) {{{ 8 + 4 = 2*( 2 + 4 ) }}}
(2) {{{ 12 = 2*6 }}}
(2) {{{ 12 = 12 }}}
OK