I have an Organisation object

```
public class Organisation
{
    OrgId {get....}
    OrgName {get...}
    AccountTypes { get....} //this is of type List<AccountType>
}

```

and an AccountType object

```
public class AccountType
{
    AccountTypeId {get....}
    AccountTypeName {get...}
}

```

I'm looking for a way to look through the existing Organisations List and remove AccountTypes from each organisation where the account types are not found in another list of AccountTypes (which would be a post back from a browser).

Would I do something like?

```
var foundOrgs = from org in orgs
                where org.OrganisationId == Convert.ToInt32(hash["orgId"])
                select org;
Organisation organisation = foundOrgs.ElementAt(0);
organisation.AccountTypes.Clear();
organisation.AccountTypes = // What goes here?

```

I'm looking to do a Linq query that will compare one list with another and return only those items where the AccountTypeIDs match, or are present.