Well, the messages that get reported end up with me somehow.
And the link I have posted is totally relevant to your question "What is equation question?", because it explains exactly what an equation question is.
It does not make sense to repeat the basics in the forum. So Tony posted a solution, and you asked about what an equation question is. And I gave you a link where you can read about equation questions. I could have written "rtfm", but no, I even posted the link where you can find the information, yet still you are complaining.
This forum is mainly run by volunteers, so we do this in our spare time. You will see that people are more than willing to help here, but if you are not willing to read links that we are posting, I guess it is not worth answering your questions anymore, because you then you are not here to learn, but to get work done for you for free.
If you have specific questions/problems with equation questions, then this is the place for the forum. But if you don't know what an equation question is, the best way is to read about it in the manual, because as I said, it makes no sense to repeat it here. Thus I posted the link.
And I think the recommendation to read through the question types page in the manual is one of the best advice I can give you about how to learn how to use Limesurvey. It helped me to better understand the tool, and it will help you as well, I am sure.