Our math team had m students last year, but this year it has already n students! By what percent did the number of students grow?

I'm in need of the full answer, not just the formula! (I'm sorry!)

Last year we had M students.

This year we have N students.

Now, the question ask "by what percentage the number of students grow".

So we are considerating a growth, this means that we must think that M as the 100%.

Then we have that N - M is the difference between the students of last year and this year.

this means that this year we have N - M more students that last year, so the percentage of growth is:

((N - M) / M) * 100%

Now you need to replace the values for N and M.

You also can notice that if N is smaller than M, you will have a negative percentage, this means that instead of a growth, we have a decrease in the number of students.