CREATE TABLE [Work.Work] (
    [WorkCode] INT          IDENTITY (1, 1) NOT NULL
)

CREATE TABLE [Work.WorkContributor] (
    [WorkContributorID]    INT            IDENTITY (1, 1) NOT NULL,
    [WorkCode]             INT            NOT NULL,
    [MechanicalShare]      DECIMAL (9, 4) NOT NULL,
)

select * from [Work.Work] w
CROSS APPLY (select isnull(sum(wc.MechanicalShare), 0) as Sum from [Work.WorkContributor] wc
				where wc.WorkCode = w.WorkCode
					
	) subQuery
where subQuery.Sum between 99.9 and 100.1

var works = entityFrameworkContextObject.Work_Work.AsNoTracking();
works = from w in works
                        where ((99.9m < (from wc in w.Work_WorkContributor
                                     select new
                                     {
                                         toSum = wc.MechanicalShare
                                     }
                                ).Select(x => x.toSum).Sum()
                               )
                               &&
                               (100.1m > (from wc in w.Work_WorkContributor
                                       select new
                                       {
                                           toSum = wc.MechanicalShare
                                       }
                                ).Select(x => x.toSum).Sum()
                               )
                              )
select w;

SELECT 
    [Project2].[WorkCode] AS [WorkCode]
    FROM ( SELECT 
        [Project1].[WorkCode] AS [WorkCode], 
        [Project1].[C1] AS [C1], 
        (SELECT 
            SUM([Extent3].[MechanicalShare]) AS [A1]
            FROM [dbo].[Work.WorkContributor] AS [Extent3]
            WHERE [Project1].[WorkCode] = [Extent3].[WorkCode]) AS [C2]
        FROM ( SELECT 
            [Extent1].[WorkCode] AS [WorkCode], 
            (SELECT 
                SUM([Extent2].[MechanicalShare]) AS [A1]
                FROM [dbo].[Work.WorkContributor] AS [Extent2]
                WHERE [Extent1].[WorkCode] = [Extent2].[WorkCode]) AS [C1]
            FROM [dbo].[Work.Work] AS [Extent1]
        )  AS [Project1]
    )  AS [Project2]
    WHERE (99.9 < [Project2].[C1]) AND (100.1 > [Project2].[C2])