Step-by-step explanation:
[tex]let \: the \: age \: of \: charmaine \: be \: x[/tex]
[tex]according \: to \: question[/tex]
[tex]4 + x = 16[/tex]
[tex]x = 16 - 4[/tex]
[tex]12[/tex]
[tex]so \: the \: age \: of \: shaun \: is \: [/tex]
[tex]x + 4[/tex]
[tex]12 + 4[/tex]
[tex]16[/tex]
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