They may mean 35 to 50% of take-home pay.
Thats one of the problems with withholding. Very few people actually know what their income is. Do yourself a little study. Stop 10 strangers on the street or 10 coworkers you are comfortable asking.
Ask them "How much money did you make last year?"
Most will answer by saying "Well, I take home..."
Then stop them and say "Thats not what I asked. I asked how much you made." Most will have no idea.