You have the following data set:
x 1 0 -3
y 5 4 1
Where y is a function of x. In order to translate the previous function 2 unitd downward, you take into account that you subtract 2 units to the given values for y. Then, you have:
y (5-2) (4-2) (1-2)
which becomes:
y 3 2 -1
Finally, the given table becomes:
x 1 0 -3
y 2 2 -1