Question 656275
How old am I now?
Let {{{ x }}} = my age now
{{{ x - 10 }}} = my age 10 years ago
Let {{{ y }}} = my Daughter's age now
{{{ y - 10 }}} = my Daughter's age 10 years ago
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given:
(1) {{{ x - 10 = 14*( y - 10 ) }}}
(2) {{{ x = 4y }}}
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Substitute (2) into (1)
(1) {{{ 4y - 10 = 14*( y - 10 ) }}}
(1) {{{ 4y - 10 = 14y - 140 }}}
(1) {{{ 14y - 4y = 140 - 10 }}}
(1) {{{ 10y = 130 }}}
(1) {{{ y = 13 }}}
and. since
(2) {{{ x = 4y }}}
(2) {{{ x = 4*13 }}}
(2) {{{ x = 52 }}}
I am 52 now and my Daughter is 13
check:
(1) {{{ x - 10 = 14*( y - 10 ) }}}
(1) {{{ 52 - 10 = 14*( 13 - 10 ) }}}
(1) {{{ 42 = 14*3 }}}
(1) {{{ 42 = 42 }}}
OK