Given the following banking database, formulate a relational algebra expression for each of the following questions. select should be performed before any join operation. notation: use the symbol s for select, p for project, j for inner join, #for natural join, u for left join, rj for right join, r for rename, and f for function. type your answer; hand-writing is not acceptedbranch(branch_name, branch_city, assets) customer (customer_name, customer_street, customer city) loan (loan_ borrower (customer_name, loan_number) account (account_number, branch_name, balance) depositor (customer_name, account_number) number, branch_name, amount) a. find the names of all borrowers who have a loan in branch "downtown" and whose loan values are higher than $20,000 b. among customers with loans, list each of the customer's name, the number of loans borrowed by the customer, and the average loan amount of the customer. a. b.