Answer:
62, 63, 64
Explanation:
The middle integer of three consecutive integers will be the average of them. That is, it will be their sum, divided by 3.
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The middle integer is 189/3 = 63.
The three consecutive integers are 62, 63, 64.
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Additional comment
If you'd like to write an equation that tells you the same thing, let x represent the middle integer. Then the lower one is x-1, and the upper one is x+1. Their sum is ...
(x-1) +x +(x+1) = 189
3x = 189 . . . . . . . . . . . . simplify
x = 189/3 = 63 . . . . . . . divide by the coefficient of x
(x-1) = 63-1 = 62 . . . . . . find the other two integers
(x+1) = 63+1 = 64