Answer
All three will decrease by the amount subtracted.
Work Step by Step
If a value, a, is subtracted from all of the terms, the average will decrease by that amount as well, for all of the values decreased by the same amount.
Similarly, the median data point will be shifted by a value a, so it will go down by that amount as well.
Lastly, the mode will decrease by a value a. Since all of the values in the mode will decrease by a, the mode will decrease by that amount as well.
