Question 1126712
Let {{{ a }}} = Tony's age now
Let {{{ b }}} = Marvin's age now
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(1) {{{ a = ( b + 1 ) - 5 }}}
(2) {{{ a - 6 = (1/2)*( b - 6 ) }}}
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(1) {{{ a - b = -4 }}}
(2) {{{ 2a - 12 = b - 6 }}}
(2) {{{ 2a - b = 6 }}}
subtract (1) from (2)
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(2) {{{ 2a - b = 6 }}}
(1) {{{ -a + b = 4 }}}
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{{{ a = 10 }}}
and
(1) {{{ 10 - b = -4 }}}
(1) {{{ b = 14 }}}
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Tony is 10 
Marvin is 14
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check:
(2) {{{ a - 6 = (1/2)*( b - 6 ) }}}
(2) {{{ 4 = (1/2)*8 }}}
(2) {{{ 4 = 4 }}}
OK