Question 988006
Let {{{ k }}} = age of kai kai in 2013
Let {{{ j }}} = age of jia jia in 2013
{{{ k + 9 }}} = age of kai kai in 2022
{{{ j + 9 }}} = age of jia jia in 2022
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(1) {{{ k + j = 11 }}}
(2) {{{ k + 9 = 3j }}}
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(2) {{{ k = 3j - 9 }}}
Substitute (2) into (1)
(1) {{{ 3j - 9 + j = 11 }}} 
(1) {{{ 4j = 20 }}}
(1) {{{ j = 5 }}}
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and
(2) {{{ k = 3*5 - 9 }}}
(2) {{{ k = 15 - 9 }}}
(2) {{{ k = 6 }}}
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{{{ j + 1 = 6 }}}
{{{ k + 1 = 7 }}}
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kai kai is 7 in 2014
Jia Jia is 6 in 2014