Question 1098043
Let {{{ a }}} = my age now
Let {{{ b }}} = my brother's age now
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(1) {{{ a = 3b }}}
(2) {{{ a + 5 = (5/2)*( b + 5 ) }}}
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Multiply both sides of (2) by {{{ 2 }}}
(2) {{{ 2a + 10 = 5b + 25 }}}
(2) {{{ 2a - 5b = 15 }}}
Plug (1) into (2)
(2) {{{ 2*( 3b ) - 5b = 15 }}} 
(2) {{{ 6b - 5b = 15 }}}
(2) {{{ b = 15 }}}
and
(1) {{{ a = 3b }}}
(1) {{{ a = 3*15 }}}
(1) {{{ a = 45 }}}
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I an 45 and my brother is 15
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check:
I am 3 times as old as my brother TRUE
(2) {{{ a + 5 = (5/2)*( b + 5 ) }}}
(2) {{{ 45 + 5 = (5/2)*( 15 + 5 ) }}}
(2) {{{ 50 = (5/2)*20 }}}
(2) {{{ 50/20 = 5/2 }}}
(2) {{{ 5/2 = 5/2 }}}
OK