Question 502462
Let {{{f}}} = father's age now
Let {{{s}}} = Son's age now
given:
(1) {{{ f = 3s }}}
(2) {{{ f + 20 = 2*( s + 20 ) }}}
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(2) {{{ f + 20 = 2s + 40 }}}
(2) {{{ f - 2s = 20 }}}
Substitute (1) into (2)
(2) {{{ 3s - 2s = 20 }}}
(2) {{{ s = 20 }}}
The Son is now 20
check:
(1) {{{ f = 3s }}}
(1) {{{ f = 3*20 }}}
{{{ f = 60 }}}
and
(2) {{{ f + 20 = 2*( s + 20 ) }}}
(2) {{{ 60 + 20 = 2*( 20 + 20 ) }}}
(2) {{{ 80 = 2*40 }}}
(2) {{{ 80 = 80 }}}
OK