Consider the following schema of a company database: Employees(eid: integer, ename: string, address: string, supereid: integer) Departments(did: integer, dname: string) Projects(pid: integer, pname: string, did: integer) Works_on(eid: integer, pid: integer, hours: integer) Each Employee has a supervisor (another Employee) referenced by his/her supereid. Projects are uniquely assigned to a Department. The Works_on relation records which Employee works on which Project for how many hours a week. Formulate each of the following queries in relational algebra and SQL queries. (a) ( 6 points) For each Employee, find his / her name and the name of his / her supervisor. (b) (7 points) Find the eids of Employees who work on a project of every Department, i.e. find the eids of Employees who work for (a project of) every Department. (c) (7 points) Find the pid of Projects of Department with dname = "Toys" for which at least two different Employees work