I got this answer because since we don't have the minuend( first number of the subtraction problem) so we have to work with the numbers we have. We know that the sum is 8 and since this is a subtraction problem we will add 8 and 2.5 this leaves us with 10.5 so this is what the final rendering of the equation will look like, 10.5-2.5= 8.
