Answer:
1.25 * N
Explanation:
We have to increase N by 25%.
The first thing is to say how the percentage works in these cases, N would be our 100% and the increase would be 25% in this case, therefore, the initial value must be added (that is, N, 100%) and to that if add 25% of the initial value (that is, + 25% N).
Thus:
100% * N + 25% * N = N * (100% + 25%)
N * (125%) = 1.25 * N
So to increase N is 25% it would be 1.25 * N