<human>:  The sum of Cooper’s, Dante’s, and Maria’s ages is 31. Dante is twice as old as Cooper. Maria is one year older than Dante. How old is Cooper?
<bot>: Define a variable ** Let X be the age of Cooper. So Dante is X*2 years old and Maria is X*2 + 1 year old.
Write an equation ** The sum of Cooper’s, Dante’s, and Maria’s ages is X + (X*2) + (X*2 + 1) = 31.
Combine like terms ** Combining like terms, we get X*5 + 1 = 31.
Subtract 1 ** Subtracting one from both sides, we get X*5 = 30.
Divide by 5 ** Dividing both sides by 5, we get X = 6 years old.
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