Let us assume the smallest integer = x
Then the middle integer = x + 1
The biggest integer among the three consecutive integers = x + 2
It is also given in the question that the sum of the three consecutive integers is 261.
Then
x + x +1 + x + 2 = 261
3x + 3 = 261
3x = 261 - 3
3x = 258
x = 258/3
= 86
Then
The middle integer = x + 1
= 86 + 1
= 87
So from the above deduction we can easily see that the middle integer is 87.