Question 1020663
Let {{{ s }}} = the son's age now
Let {{{ f }}} = the father's age now
{{{ f - s }}} = the difference in their ages
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When the son was 2, the father was:
2 + [ the difference in their ages ]
{{{ 2 + f - s }}}
That was when the father was 
the son's present age, so
{{{ s = 2 + f - s }}}
(1) {{{ 2s - f = 2 }}}
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When the father is {{{ 68 }}},
then {{{ 68 }}} - [ the difference in their ages ] = 
" your age " which is the father's present age, so
{{{ f = 68 - ( f - s ) }}}
{{{ f = 68 - f + s }}}
(2) {{{ -s + 2f = 68 }}}
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Multiply both sides of (1) by {{{ 2 }}} and add the equations
(1) {{{ 4s - 2f = 4 }}}
(2) {{{ -s + 2f = 68 }}}
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{{{ 3s = 72 }}}
{{{ s = 24 }}}
and
(1) {{{ 2s - f = 2 }}}
(1) {{{ 2*24 - f = 2 }}}
(1) {{{ f = 48 - 2 }}}
(1) {{{ f = 46 }}}
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The father's present age is 46
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check:
The difference in their ages is: {{{ 46 - 24 = 22 }}}
"A father said to his son, When I was your age,"
when the fathers was: {{{ 24 }}}
" you were 2 years old."
{{{ 24 - 22 = 2 }}} OK
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"When I reach your age, "
when the son is {{{ 46}}},
The father will be {{{ 46 + 22 = 68 }}} OK