My 2 toilets are clugged. Just before that, bubbles come up in my toilets when someone takes a shower. What is the cause and how can I fix it? I have a small 50' snake and a 6 foot cable reach (RIDGID).

Your main sewer is clogged. You need to find clean out and clean it. If you don't have clean out you can try to snake it through the vent on the roof or remove one of the toilets and snake it through the closet ring.

To clean sewer main line, you will need at least 5/8" x 75" snake. Clog can be right where the two toilet pipes meet or it can be further down the slope.

You can rent a snake from Home Dept for couple of hours.