Question 723645
Let {{{ f }}} = Father's age now
Let {{{ s }}} = Son's age now
given:
(1) {{{ s = (1/3)*f }}}
(2) {{{ f + 17 = 2*( s + 17 ) }}}
-------------------------
(1) {{{ f = 3s }}}
(2) {{{ f + 17 = 2s + 34 }}}
(2) {{{ f - 2s = 17 }}}
By substitution,
(2) {{{ 3s - 2s = 17 }}}
(2) {{{ s = 17 }}}
and, since
(1) {{{ f = 3s }}}
(1) {{{ f = 3*17 }}}
(1) {{{ f = 51 }}}
The Father is 51 now
check:
(2) {{{ f + 17 = 2*( s + 17 ) }}}
(2) {{{ 51 + 17 = 2*( 17 + 17 ) }}}
(2) {{{ 68 = 2*34 }}}
(2) {{{ 68 = 68 }}}
OK