Relational Algebra in SQL

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Sorry about the imgur link But the picture wont let me paste in here.

(1) List the departments (department name, department number) that have a location in Seattle.

(2) List the names of employees (lname, fname) who have a dependent with the same first name as themselves. (Dependent_name is the first name of the dependent)

(3) Retrieve the names of employees (lname, fname) in department 8 who work more than 10 hours per week on the 'RD' project. (RD is the project name.)

(4) Find the names of employees (lname, fname) who are directly supervised by 'Mary Huber'.