Question 763410
Let {{{ f }}} = my father's age now
Let {{{ d }}} = my daughter's age now
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given:
(1) {{{ f = 13d }}}
(2) {{{ f + 1  = 11*( d + 1 ) }}}
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(2) {{{ f + 1 = 11d + 11 }}}
(2) {{{ f - 11d = 10 }}}
Substitute (1) into (2)
(2) {{{ 13d - 11d = 10 }}}
(2) {{{ 2d = 10 }}}
(2) {{{ d = 5 }}}
and, since
(1) {{{ f = 13d }}}
(1) {{{ f = 13*5 }}}
(1) {{{ f = 65 }}}
My father is 65
check:
(2) {{{ f + 1  = 11*( d + 1 ) }}}
(2) {{{ 65 + 1  = 11*( 5 + 1 ) }}}
(2) {{{ 66 = 11*6 }}}
(2) {{{ 66 = 66 }}}
OK