I would like to apply a simple if formula to a multiple choice question

I would like the form to work such that you only need to complete certain sections if you pick certain options from an initial multiple choice question.

For example the multiple choice is a list of services - of which you can take one or more options. 

e.g.

Service A

Service B

Service C

Then you have to complete detailed sections of the form based on this.

e.g If Sevice A selected show Section A

If Service A and Service C selected show Section A and Section C.

You can use the Conditions for this purpose.

I have created a test document based on your description. You can clone the form on your end if you want.

You should also use the Section Collapse Field for your sections.

https://www.jotform.com/help/297-Show-or-Hide-Multiple-Fields-at-Once-Using-the-Section-Collapse-Field

Please kindly check the following steps:

1- Create Multiple Choice element to your form.

2- Add Section Collapse Fields as many as you required. In this case, I have added 3 of them.

3- Then, click on the gear icon on the section collapse field. You should set hidden visibility settings.

4- Click on Conditions, then Show/Hide Field option.

Here is the link of the test form that I have created for you:

https://form.jotform.com/91054393264962

You can clone the form and check the conditions here, as well.

I hope this helps!

If you need any further assistance, please let us know.