Respuesta :

The three numbers are 2, 7 and x.

Ther sum is
 2 + 7 + x = 9 + x

 Because the arithmetic mean is 12, therefore
(9 + x)/3 = 12
9 + x = 12*3 = 36
x = 36 - 9 = 27

Answer:  x = 27

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