Write SQL query to solve given problem: What is the average amount of rent that Christy Vargas paid?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT AVG(T2.amount) FROM customer AS T1 INNER JOIN payment AS T2 ON T1.customer_id = T2.customer_id WHERE T1.first_name = 'CHRISTY' AND T1.Last_name = 'VARGAS'