In some texts the hypotheses would be written like so:
H0: m = 25.
H1: m > 25
Reject H0 if P < 0.01
That is, the null hypothesis is written as it appears in the problem. Our book takes a slightly different point of view: The only concern is that the mean is greater than 25. We don't care if is less than 25 so write the null hypothesis to include less than 25. In our book the null hypothesis and alternative hypothesis always contradict each other. This way is less confusing when it comes to recognizing the type of test.