students(sid,name,age,gpa)

courses(cid,deptid, description)

professors(ssn,name,address,phone,deptid)

enrollment(sid,cid,section

teaches(cid,section,grade). cid makes reference to the courses table. ,ssn). cid, section makes reference to the enrollment table

(a) For each student, compute the actual GPA based on enrollment: (A=4, B=3, C=2, D=1, grades of F do not count).

(b) For each pair of professors, determine the number of students that take classes with both. Do not double count students.