986÷34×138-2005
=(986+34-34)÷34×138-2005
=(1020÷34-34÷34)×138-2005
=[(10×3×34)÷34-1]×138-2005
=(30-1)×(70-1)×2-2005
=(2100-70-30+1)×2-2005
=2001×2-2001-4
=2001-4
=1997