= (1988 x 1996 + 1997 x 11 + 1985) : (1997 x 1996 - 1995 x 1996)
= (1988 x 1996 + (1996 + 1) x 11 + 1985) : (1996 x (1997 - 1995))
= (1988 x 1996 + 1996 x 11 + (11 + 1985)) : (1996 x 2)
= (1996 x (1988 + 11) + 1996 : (1996 x 2)
= (1996 x 1999 + 1996) : (1996 x 2)
= (1996 x 1999 + 1996 x 1) : (1996 x 2)
= (1996 x (1999 + 1)) : (1996 x 2)
= 1996 x 2000 : 1996 x 2
= 2000 : 2
= 1000.