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Nellie is 8 years older than Cristal. Geoffrey is 3 times as old as Cristal. Paris is 5 years younger than Cristal. The combined age of the four is 63
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See how everyone's age is related to Cristal?
Let c be Cristal's age.
Nellie c+8
Cristal c
Geoffrey 3c
Paris c-5
SUM 63
You should obviously know what to do with that.