Answer: 2.1, I don't really know how to show a model for this, its just that when you multiply 3 and 7 you get 21, when you do 0.7 and 3, you just put the decimal place between the 2 and 1.
Well, we know that the two consecutive numbers have to be negative, because if it was positive, the smaller number multiplied by two would be much greater. (unless 1 and 2). So, by guessing and checking, we will get -13 and -14 :)
