Consider the following two relations, write sql queries for the following.

Employee$($EmployeeID$,$ FirstName, LastName, DepartmentID, and Salary$)$

Department$($DepartmentID$,$ DepartmentName$)$

$1)$ Write an insert query to insert the following employee $-$ John Brown with an employee id of S$101$ and salary of $$80,000$

$2)$ Retrieve the FirstName, LastName, and Salary of employees who work in the 'Sales'$($DepartmentName$)$ and have a salary greater than $$50,000$

$3)$ Retrieve the FirstName, LastName, and Salary of employees who have a salary greater than the average salary of all employees.