3 - Way problem

When I flush my toilet, it backflows into my bathtub or sink, also the sink makes this gurggling sound if it doesn't backflow. Can you tell me what's going on and how to fix it?:eek:

You have a clog in the drain line downstream from the tub and lavatory that the toilets discharge hits and then backs up. The noise you hear is the bubble air that the clog sends ahead of it as it goes through the water seal in the lavatorys trap. The solution is to snake out the lavatorys vent from the roof. Putout enough cable to hit the base of the vent and about 20 feet more to clear the drain line. Good luck, Tom

Thank you for all your help