Answer:
to find a y-value, plug in any number for x in the equation and then solve the equation for y.
if you're given a table that has x-values filled in, plug each of those in for x in order to solve for their corresponding y-value.
if the table is blank, pick whatever numbers you want to use as x-values. don't use any numbers that are astronomically large, though. i always find that the best, most basic numbers to stick with are -2, -1, 0, 1, and 2.
i hope this helps! have a lovely day <3