Querying derived table in Entity Framework + using aggregates

Question

I do not even know where to start with this.

How do I query a derived table in Entity Framework?

Here is a SQL query I want to translate to Entity:

SELECT
    count(question_id)
FROM
(
    SELECT
        question_id 
    FROM
        user_answers
    WHERE
        user_id = 'xyz'
        AND
        correct = 1
    GROUP BY
        QUESTION_ID
    HAVING
        count(*) > 1
) as b

Can anybody provide any insight into this?

Many thanks!

Kevin