"صَحيفة اَلْأُسْتاذ في مَكْتَب اَلْأُسْتاذ."
Translation:The professor's newspaper is in the professor's office.
The professor's newspaper is in the office of the professor, means the same. Also, The newspaper of the professor is in the professor's office, means the same. Either or both should be accepted.
I am waiting to get a reply for my above comment as well as comment made elsewhere. The professor's office can be stated equivalently as The office of the professor. Why are we using the possessive case all the time? Please someone explain this.