Question 772462
Let {{{ f }}} = my age now
Let {{{ s }}} = my son's age now
{{{ f - 2 }}} = my age 2 yrs ago
{{{ s - 2 }}} = my son's age 2 yrs ago
{{{ f - 8 }}} = my age 8 yrs ago
{{{ s - 8 }}} = my son's age 8 yrs ago
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(1) {{{ f-2 = 4*( s-2 ) }}}
(2) {{{ f-8 = 10*( s-8 ) }}}
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(1) {{{ f - 2 = 4s - 8 }}}
(1) {{{ f - 4s = -6 }}}
and
(2) {{{ f - 8 = 10s - 80 }}}
(2) {{{ f - 10s = -72 }}}
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Subtract (2) from (1)
(1) {{{ f - 4s = -6 }}}
(2) {{{ -f + 10s = 72 }}}
{{{ 6s = 66 }}}
{{{ s = 11 }}}
Plug this result back into either equation
(1) {{{ f-2 = 4*( 11-2 ) }}}
(1) {{{ f - 2 = 36 }}}
(1) {{{ f = 38 }}}
My son is 11 now
check:
(2) {{{ 38-8 = 10*( 11-8 ) }}}
(2) {{{ 30 = 10*3 }}}
(2) {{{ 30 = 30 }}}
OK