My bathtub drains slow and while draining the toilet bubbles. Then it is slow to flush. I have had the plumbing line cleared of roots ---3 times and added root destroy to the lines. Any suggestions?

There is an air pipe somewhere that is connected to your sewer pipe... maybe it is clogged with something... the pipe has to get air to flush properly..

That would be a vent stack which exits through the roof. You can rod from the roof using enough snake to reach roof to basement floor plus 15'. The bubbles in the toilet is the sewer gas and air in your drain trying to vent through the toilet because the vent stack is clogged.

My bathtub drains slow and while draining the toilet bubbles. Then it is slow to flush. I have had the plumbing line cleared of roots ---3 times and added root destroy to the lines. Any suggestions?
I paid a plumber to clear the vent drain, already and he snaked the main line twice.

If the plumber did this work and the drain was still slow did he have an explanation? Did he get paid even though he made not repair?

My bathtub drains slow and while draining the toilet bubbles. Then it is slow to flush. I have had the plumbing line cleared of roots ---3 times and added root destroy to the lines. Any suggestions?
He thinks roots, he also, thinks it is clear. It was OK for a couple weeks then stated again. He suggested Root Kill, which we did last Friday on Monday, still a problem. This morning, after the tub drained and the toilet bubbled the water lever in the toilet dropped extremely low. I don't know whether to try more root kill this soon. I don't have time to meet the plumber this week so I was trying to resolve the problem myself. He has been paid, he claims that the lines are clear when they leave, which they are, but they don't stay clear.

I'm not on site so its difficult to tell you much other than I question your plumbers skills and equipment. Roots don't grow that quickly so if he truly cleared the line all the way to the city riser they'd be flowing. Also, most plumbers us a SeeSnake which is a camera rodder so they can actually see broken pipes or roots. Your guy doesn't seem to do this. Root kill is a waste of money at this point. Its better at preventing root growth but doesn't make the mass disappear once its killed, a 3" cutter would do that.