Question 658385
Let {{{ p }}} = Paula's age now
Let {{{ b }}} = Bob's age now
given:
(1) {{{ p = b + 12 }}}
(2) {{{ b + 4 = (2/3)*( p + 4 ) }}}
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(2) {{{ 3b + 12 = 2p + 8 }}}
(2) {{{ 2p - 3b = 4 }}}
Substitute (1) into (2)
(2) {{{ 2*( b + 12 ) - 3b = 4 }}}
(2) {{{ 2b + 24 - 3b = 4 }}}
(2) {{{ -b = -20 }}}
(2) {{{ b = 20 }}}
and
(1) {{{ p = b + 12 }}}
(1) {{{ p = 20 + 12 }}}
(1) {{{ p = 32 }}}
Paula is 32
Bob is 20 
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check:
In 4 years Paula is 36
In 4 years Bob is 24
{{{ 24 = (2/3)*36 }}}
Divide both sides by {{{12}}}
{{{ 2 = (2/3)*3 }}}
{{{ 2/3 = 2/3 }}}
OK