Question 866725
Let {{{ m }}} = mother's age now
Let {{{ s }}} = son's age now
{{{ m - 1 }}} = mother's age 1 year ago
{{{ s - 1 }}} = son's age 1 year ago
{{{ m + 6 }}} = mother's age in 6 years
{{{ s + 6 }}} = son's age in 6 years
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(1) {{{ m - 1 = 4*( s - 1 ) }}}
(2) {{{ m + 6 = 2*( s + 6 ) + 5 }}}
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(1) {{{ m - 1 = 4s - 4 }}}
(1) {{{ 4s - m = 3 }}}
and
(2) {{{ m + 6 = 2s + 12 + 5 }}}
(2) {{{ m + 6 = 2s + 17 }}}
(2) {{{ -2s + m = 11 }}}
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Add (1) and (2)
(2) {{{ -2s + m = 11 }}}
(1) {{{ 4s - m = 3 }}}
{{{ 2s = 14 }}}
{{{ s = 7 }}}
and, since
(1) {{{ m - 1 = 4*( s - 1 ) }}}
(1) {{{ m - 1 = 4*( 7 - 1 ) }}}
(1) {{{ m - 1 = 24 }}}
(1) {{{ m = 25 }}}
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The mother is 25 
The son is 7
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check:
(2) {{{ m + 6 = 2*( s + 6 ) + 5 }}}
(2) {{{ 25 + 6 = 2*( 7 + 6 ) + 5 }}}
(2) {{{ 31 = 2*13 + 5 }}}
(2) {{{ 31 = 26 + 5 }}}
(2) {{{ 31 = 31 }}}
and
(1) {{{ m - 1 = 4*( s - 1 ) }}}
(1) {{{ 25 - 1 = 4*( 7 - 1 ) }}}
(1) {{{ 24 = 4*6 }}}
(1) {{{ 24 = 24 }}}
OK