Hey there!
So, just by adding this expression, we know that 8 + 20 = 20.
So, by doing this, this give's us a hint that, that answer would be around there.
So,[tex] 8 - 20 = -12[/tex]
Your correct answer would be [tex]\boxed{\boxed{-12}}[/tex]
Hope this helps.
~Jurgen
