Please help me with this question. I would Really appreciate it.

student takes ID course id sec id semester ID name dept name tot_cred grade section course course id title dept name credits department dept name building budget advisor sec i0 semester ear building room_no time slot id time slot time slot day start time end_time prere instructor classroonm ID name dept name salary room n0 capacity teaches ID course id sec id semester ear Figure 2.8 Schema diagram for the university database. Find the ID's of all instructors who have taught or are teaching a course from a different department than the one to which they are assigned. For example, the result would include Electrical Engineering professors who teach Computer Science courses. Express your answers in relational algebra. Your queries should NOT include unneeded relations