Write the following queries in relational algebra: a. Find the names of all employees whose salary is higher than 500K; b. Find the names of all employees who work more than 15 hours on project X (Pname); c. Find the ids of those who work on a project located in Brooklyn but never in a project located in Long Island; d. Return the names of those who have the lowest salary among all employees whose age is between 35 and 40 ; e. Find the names of employees whose salary is higher than that of his/her supervisor; f. Find the names of all employees who have a dependent with the same name as themselves; g. Find the names and SSNs of employees who worked on EVERY project located in Brooklyn; h. Find the names of those who worked on exactly three projects