I would suggest that the parameters shouldn't be ints, anyway. Someone might want to know the percentage of a fractional number. Someone also might think that the return type has been coerced to match an the input arguments (integers), rather than having been set by PHPs "autotyping".
I would also suggest that the relationship, a/b*100, is far too simple to waste the overhead of a function call. On the other hand, I come from the days when resources weren't so abundant that one could be profligate with them.