 
 <translate> Let X be the age of Cooper. So Dante is X * 2 years old and Maria is X * 2 + 1 year old. The sum of Cooper’s, Dante’s, and Maria’s ages is X + (X * 2) + (X * 2 + 1) = 31. Combining like terms, we get X * 5 + 1 = 31. Subtracting one from both sides, we get X * 5 = 30. Dividing both sides by 5, we get X = 6 years old.
The answer: 6. <ibo> Ka X bụrụ afọ ole Cooper dị. Ya mere, Dante dị afọ X * 2 na Maria dị afọ X * 2 + 1. Nchịkọta nke afọ ndụ Cooper, Dante, na Maria bụ X + (X * 2) + (X * 2 + 1) = 31. Na ijikọta okwu ndị yiri ya, anyị na-enweta X * 5 + 1 = 31. Anyị wepụ otu n'akụkụ abụọ, anyị na-enweta X * 5 = 30. N'ịkewa akụkụ abụọ site na 5, anyị na-enweta X = 6 afọ. Azịza ya bụ: 6. 