Relational algebra question

30 points] Consider the Question.7 following relations EMPLOYEE(e-id, ename, salary, address, d-id) DEPARTMENT(d-id, manager-id) where the manager of a department is also an employee. Provide a Relational Algebra expression for each of the following queries: (a) [5 points] Return all the pairs of employee id and the corresponding manager id. (b) [10 points] Return all the pairs of employee name and the corresponding manager name. (c) [10 points] Return the id of the employees who have a salary higher than the salary of their managers