CREATE TABLE #N(n INT NOT NULL PRIMARY KEY CLUSTERED );
;WITH N(n) AS (SELECT 1 UNION ALL SELECT n+1 from N WHERE n < 1000) 
INSERT INTO #N SELECT * FROM N OPTION (MAXRECURSION 0);

DECLARE @x1 INT, @x2 INT;
SET @x1 = 9; SET @x2 = 6;

SELECT TOP 1
	@x1*N1.n
FROM
	#N N1 CROSS JOIN #N N2
WHERE
	N1.n * @x1 = N2.n*@x2
ORDER BY 1;

DROP TABLE #N;

CREATE TABLE #N(n INT NOT NULL PRIMARY KEY CLUSTERED );
;WITH N(n) AS (SELECT 2 UNION ALL SELECT n+1 from N WHERE n < 1000) 
INSERT INTO #N SELECT * FROM N OPTION (MAXRECURSION 0);

DECLARE @x1 INT, @x2 INT;
SET @x1 = 7; SET @x2 = 6;


 
SELECT TOP 1
	 N1.n 
FROM
	#N N1
WHERE
	    @x1*1.0  /  N1.n     =  @x1	/N1.n  
	and  @x2*1.0 / N1.n      = @x2 / N1.n  
UNION 
SELECT 1	
ORDER BY 1 desc;

DROP TABLE #N;