Consider a DB schema consisting of the following relation schemes:

-> Person ( _name_, age, gender) - Describes person -> Frequents ( _name_, _pizzeria_ ) - Frequency of a person -> Eats ( _name_, _pizza_ ) - What a person is eating -> Serves ( _pizzeria_, _pizza_, price ) - Information about serves

* Keys are _underlined_ Now, express the following queries in Relational Algebra: 1. List all the pizzerias frequented by at least one person under the age of 18. 2. Fetch the names of all females who eat either mushroom or pepperoni pizza (or both). 3. Get all the pizzerias that serve at least one pizza that Amy eats for less than $10.00. 4. Find all the pizzerias that are frequented by only females or only males. 5. For every individual, find all pizzas a person eats that are not served by any pizzeria the person frequents. Find those person (name) / pizza pairs. 6. List the names of all the people who frequent only pizzerias serving at least one pizza they eat. 7. Find the pizzeria serving the cheapest pepperoni pizza. For a tie, return the cheapestpepperoni pizzerias.