Question 1136563
Let {{{ a }}} = the man's age now
Let {{{ b }}} = his son's age
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(1) {{{ a - 4 = 6*( b - 4 ) }}}
(2) {{{ a + 12 = 2*( b + 12 ) }}}
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(1) {{{ a - 4 = 6b - 24 }}}
(1) {{{ a - 6b = -20 }}}
(1) {{{ -a + 6b = 20 }}}
and
(2) {{{ a + 12 = 2b+ 24 }}}
(2) {{{ a - 2b = 12 }}}
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Add (1) and (2)
(1) {{{ -a + 6b = 20 }}}
(2) {{{ a - 2b = 12 }}}
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{{{ 4b = 32 }}}
{{{ b = 8 }}}
and
(2) {{{ a - 2*8 = 12 }}}
(2) {{{ a = 12 + 16 }}}
(2) {{{ a = 28 }}}
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The man is 28
The son is 8
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check:
4 yrs ago, the man was 24
4 yrs ago, son was 4
{{{ 4*6 = 24 }}}
OK
and
In 12 yrs, man will be 40
In 12 yrs, son will be 20
{{{ 40 = 2*20 }}}
OK