Answer:
25
Step-by-step explanation:
Let n be the first integer.
Then the second integer will be (n + 1).
And the third will be (n + 2).
The sum is 78. Therefore:

Solve for n. Combine like terms:

So:

Therefore:

Therefore, the first integer is 25.
So our sequene is 25, 26, and 27.
The integer closest to zero will thus be 25.