Question 419651
Let {{{a}}} = my age now
Let {{{b}}} = my sister's age now
given:
(1) {{{ a = 3b }}}
(2) {{{ a - 6 = 5*(b - 6) }}}
----------------
Substitute (1) in (2)
(2) {{{ 3b - 6 = 5*(b - 6) }}}
(2) {{{3b - 6 = 5b - 30 }}}
(2) {{{ 2b = 24 }}}
{{{ b = 12}}}
and
(1) {{{a = 3b }}}
{{{a = 36}}}
I'm 36 and my little sister is 12
check:
(2) {{{ 3*12 - 6 = 5*(12 - 6) }}}
{{{ 36 - 6 = 5*6 }}}
{{{30 = 30 }}}
OK