C 1 2   =   D S u m ( V N D C K N O   ;   K T T K ;   L e f t ( M a t k , 3 )   =   ' 1 1 1 ' ) 
 
 E 1 2   =   D S u m ( T T V N D   ;   K T S C ;   T K N O   =   ' 2 4 1 2 1 3 4 1 9 '   A N D   N G A Y C T > = V _ T U _ N G A Y   A N D   N G A Y C T < = V _ D E N _ N G A Y ) 