You will not manage to work with equations without reading about EM within the manual. But I can understand that it is overwhelming. To find out on how to address a certain question/subquestion/answer, it helps to look at the question logic files, because it shows you, how this is addressed.
Now here an example for array questions. You have two factors here that you need to take in to account: subquestions and answer options.
As you want to know the value of the answer option, you to read this into your equation, which can be done by something like this:
Code:
{questioncode_subquestioncode}
So let's assume your first question has the question code "Q1" and the subquestions are called SQ1, SQ2, SQ3 and SQ4.
So you'll get the answer code subquestion 1 like this:
So to get a sum of all responses to Q1 you would do something like:
Code:
{sum(Q1_SQ1, Q1_SQ2, Q1_SQ3, Q1_SQ4)}