We can represent our three consecutive integers as the following:
X ⇒ first integer
X + 1 ⇒ second integer
X + 2 ⇒ third integer
Since the sum is 78, we can setup our equation:
x + (x + 1) + (x + 2) = 78
~simplify
3x + 3 = 78
~subtract 3 from both sides
3x = 75
~divide both sides by 3
x = 25
Since x = 25, x + 1 would be 26 and x + 2 would be 27.
So our three consecutive integers are 25, 26, and 27.