It is certainly possible for a function decreasing over a certain interval to be negative, but no rule that says it must be. On the other hand, where the function is decreasing, the rate of change of the function must be negative.
The closest thing that goes into 26 is 24, which goes into 3 8 times. Subtract 24 from 26, and you are left with 2. The 2 you are left with will be your remainder.