Question 682053
let {{{ a }}} = my age
Let {{{ b }}} = your age
{{{ a + 5 }}} = my age in 5 yrs
{{{ b + 5 }}} = your age in 5 yrs
given:
(1) {{{ a + b = 20 }}}
(2) {{{ 2*( a + 5 ) = b + 5 + 9 }}}
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(1) {{{ b = 20 - a }}}
Substitute (1) into (2)
(2) {{{ 2*( a + 5 ) = b + 14 }}}
(2) {{{ 2*( a + 5 ) = 20 - a + 14 }}}
(2) {{{ 2a + 10 = 34 - a }}}
(2) {{{ 3a = 34 - 10 }}}
(2) {{{ 3a = 24 }}}
(2) {{{ a = 8 }}}
and, since
(1) {{{ a + b = 20 }}}
(1) {{{ 8 + b = 20 }}}
(1) {{{ b = 12 }}}
I am 8 and you are 12
check:
(2) {{{ 2*( a + 5 ) = b + 14 }}}
(2) {{{ 2*( 8 + 5 ) = 12 + 14 }}}
(2) {{{ 2*13 = 26 }}}
(2) {{{ 26 = 26 }}}
OK