Consider the bank database.
branch(branch name, branch city, assets)
customer (customer name, customer street, customer city)
loan (loan number, branch name, amount)
borrower (customer name, loan number)
account (account number, branch name, balance)
depositor (customer name, account number)
Give an expression in the relational algebra for each of the following queries:
a. Find all loan numbers with a loan value greater than $50,000.
b. Find the names of all depositors who have an account with a value greater than $9,000.
c. Find the names of all depositors who have an account with a value greater than $8,000 at the "Uptown" branch.