Question 648729
Let {{{ f }}} = the Father's age now
Let {{{ d }}} = the Daughter's age now
given:
(1) {{{ f = 4d }}}
(2) {{{ f + 6 = 3*( d + 6 ) }}}
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(2) {{{ f + 6 = 3d + 18 }}}
(2) {{{ f = 3d + 12 }}}
Substitute (1) into (2)
(2) {{{ 4d = 3d + 12 }}}
(2) {{{ d = 12 }}}
and, since
(1) {{{ f = 4d }}}
(1) {{{ f = 4*12 }}}
(1) {{{ f = 48 }}}
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The Daughter is 12 now
check:
(2) {{{ f + 6 = 3*( d + 6 ) }}}
(2) {{{ f + 6 = 3*( 12 + 6 ) }}}
(2) {{{ f + 6 = 36 + 18 }}}
(2) {{{ f = 54 - 6 }}}
(2) {{{ f = 48 }}}
OK