@Qeru is right that the first one sounds like an error in the textbook, though I wonder if it is a typo as the translated form is

and so the "2" in the denominator of the textbook's answer could be a typo for "24"

On the second question, Qeru is right about the translation but I wonder if you have made a mistake with your "+2"?

Note that the log laws allow us to write this answer in a number of forms, including:

It is wise to consider the possibility that the textbook may be incorrect, especially with more recently published textbooks. I am keeping a list of errors in the Cambridge books, for example... but another possibility is that the textbook answer is written in a different form that is equivalent to your answer. In exams, unless the form in which the answer is required is specified, all reasonable equivalent answers should be accepted, so you don't need to stress if the textbook authors choose a different form for presenting the answer. Obviously, considering whether you have made a mistake is the first option, but if you can't see one, bear in mind the other possibilities... and good job on posting here to check.

PS: It is helpful to people like me to state where a question comes from. I am planning to send Cambridge a list of mistakes / typos / formatting issues etc that I find in their books, so seeing what are errors and where they are is helpful to me. Thanks.