(C) 50
Let us assume the number be x.
From the question it is given that, number is added to 25 = x + 25
The same number is subtracted to from 25 = 25 – x
Then, the sum of the resulting numbers is = (x + 25) + (25 – x)
= x + 25 + 25 – x
= 50 + x – x
= 50 + 0
= 50