Difficult to say without seeing your answer.
That "add if its west" thing (which incidentally I don't care for) only works if you are converting from true.
More correctly:
Compass + Deviation = Magnetic
Magbetic + Variation = True
Where Easterly Deviation or Variation is POSITIVE
and Westerly Deviation or Variation is NEGATIVE
(these things are defined on starting with a compass reading and converting to true, but of course for pilot navigation we more often are doing the reverse... in which case subtracting a negative number requires addition)
Hence:
Compass 252
Deviation 3 West (-3)
Magnetic = 249
Variation 22 East (+22)
True = 271
Drifting 9 degrees to the right will give you a track of 280.
any use?
pb