Execute the following script in Query Editor to create and apply an subtraction drills stored procedure:

USE AdventureWorks
GO
CREATE PROC MathTrainerSubtraction ( @DrillNumber int , @Level int, @Result bit)
AS
BEGIN
DECLARE @Counter smallint
DECLARE @Drill table (Sequence int, [Left] int, [Right] int, Result varchar(15))
SET @Counter = 1
WHILE @Counter <= @DrillNumber
BEGIN
INSERT @Drill
SELECT @Counter, @Level * RAND(), @Level* RAND(),''
DELETE @Drill WHERE [Left] < [Right]
IF @@RowCount > 0 continue
SET @Counter = @Counter + 1
END
SELECT convert(varchar,Sequence)+'. '
+ convert(varchar, [Left])+' - '
+ convert(varchar, [Right])+ ' = '
FROM @Drill
IF @Result = 1
BEGIN
UPDATE @Drill SET Result = convert(varchar,([Left] - [Right]))
SELECT convert(varchar,Sequence)+'. '
+ convert(varchar, [Left])+' - '
+ convert(varchar, [Right])+ ' = '
+Result
FROM @Drill
END
END
GO

exec MathTrainerSubtraction 60, 30, 1
GO