When our washing machine drains our tub fills up. When we shower the tub fills up and takes many hours to drain. No problems anywhere else which tells me the main lines are not clogged. We checked the pipe from the washer to the tub area and it is clear. Our bathroom sink sits next to the tub and it drains just fine. We are stumped and can't afford a plumber right now. Any ideas? Snaking and Drain cleaners have not worked

You have a partial blockage downstream from the tub that can be snaked from the tub overflow.(see image).
Unscrew and remove the overflow plate,(The one with the drain lever) and pull out the tub stopper. You now have a clear shot at the trap. The way you were going in through the drain it ran you square into a tee that you can't get around. Now feed the cable( 1/4" best or 3/3" with a small tip. You can rent a Ridgid K50 sink cable.) About 2' down you will run into the bend of the trap. Crank and push at the same time to work around it. Your blockage will be found in the lateral pipe going to the stack. You shouldn't have to put out more then 10 or 12 feet. I have found tub and shower clogs to be mostly hair and the worm should auger into it and pull it back. After you snake pour a few pans of boiling water down the drain. This will loosen the grease and flush the mess out into the main. Hope this helps and thank you for rating my reply. TOM