8.35 b, d, f - Consider the following MAILORDER relational schema describing the data for a mail order company. PARTS(Pno, Pname, Qoh, Price, Olevel) CUSTOMERS(Cno, Cname, Street, Zip, Phone) EMPLOYEES(Eno, Ename, Zip, Hdate) ZIP_CODES(Zip, City) ORDERS(Ono, Cno, Eno, Received, Shipped) ODETAILS(Ono, Pno, Qty) Qoh stands for quantity on hand the other attribute names are self-explanatory. Specify the following queries on the MAILORDER database schema using the relational algebra: Retrieve the names and cities of employees who have taken orders for parts costing more than $50.00 . Retrieve the names of customers who have ordered parts from employees living in Wichita. Retrieve the names of customers who have not placed an order