What is the best way to conduct a complex survey (with branching)?

Question

Programming

Please advise a service for conducting surveys (questionnaires) or, maybe, a way to make such a survey yourself (I have knowledge of html and css, in principle, I think I can deal with php or js for this particular task, although, perhaps, I am too self-confident, but here, in fact, you only need a couple of "actions" - receiving data from forms and writing where necessary + reading and checking for compliance with the specified parameters).
I looked at many services, somewhere there is a branch, but nowhere is there exactly the functionality I need: the user needs to answer 7 questions, and the 8th is asked only if option 1 or 2 is selected in the first. If option 3 or 4 is selected in the first , then the 8th is skipped and the 9th is given. Also, it is desirable, but not required, that the text of the 11th question changes depending on what number the user entered when answering the 10th. Let's say in the 10th he entered 10000, then the text on the 11th looks like this: Are you ready to pay (10000+25%) for this service?

Answer 1

Received a response -> sent an ajax request -> processed formed a new question -> returned a new question -> replaced the old one with a new one -> received a new answer