Introduction
Mathematics anxiety is a negative emotion associated to mathematics related activities, such as mathematics homework. Mathematics anxiety is related to poorer mathematics performance.
The subject mathematics anxiety has been studied since the work of Richardson and Suinn in the early 1970s. There is still a growing number of publications about the subject.
There are many selfhelp videos about mathematics anxiety on YouTube. Click here to see a list of them. 
The Abbreviated Math Anxiety Scale by Hopko and colleagues, 2003 is a popular and psychometrically validated measure of mathematics anxiety.
Interesting fact: In American English, people say "math" and in British English people say "maths". A way around this is just using the word "mathematics", as has been chosen for the PsyToolkit demonstration. 
The study by Hopko and colleagues, 2003 studied more than a thousand undergraduate students. In the primary sample (N=206), the average scores were as follows (data from p.180 of the Hopko et al. paper):
Group  Score (possible values 9 to 45) 

All 
21.1 
Men 
19.5 
Women 
21.9 
In this study, women scored higher than men. That is a well known effect also found in other studies of mathematics anxiety. 
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Legal stuff
The AMAS can be used for research, but you need to acknowledge the authors and their research paper when writing about it (Hopko et al., 2003).
Technically
This is a simple scale question.
The survey code for PsyToolkit
The AMAS has been developed in the USA and uses the word "math". In this implementation, the word "mathematics" is used, so that it can be used in both the USA and the UK. If you want to just run it in the USA, you might change it back to "math", and if you just want to run it in the UK, you might change it to "maths". 
scale: amas_scale  Low Anxiety  Some Anxiety  Moderate Anxiety  Quite a bit of Anxiety  High Anxiety l: amas t: scale amas_scale o: width 50% q: Please rate each item below in terms of how anxious you would feel during the event specified.<br>  Having to use the tables in the back of a mathematics book.  Thinking about an upcoming mathematics test one day before.  Watching a teacher work an algebraic equation on the blackboard.  Taking an examination in a mathematics course.  Being given a homework assignment of many difficult problems which is due the next class meeting.  Listening to a lecture in mathematics class.  Listening to another student explain a mathematics formula.  Being given a “pop” quiz in a mathematics class.  Starting a new chapter in a mathematics book. l: amas_score t: set  sum $amas l: amas_feedback t: info q: Scores on the Abbreviated Math Anxiety Scale (AMAS) can range from 9 to 45.<br> Your score on the AMAS is {$amas_score}.
References

D.R. Hopko, R. Mahadevan, R.L. Bare, & Melassa K. Hunt. (2003). The Abbreviated Math Anxiety Scale (AMAS): Construction, Validity, and Reliability. Assessment, 10, 178182.

F.C. Richardson and R.M. Suinn (1972). Mathematics anxiety rating scale  psychometric data. Journal of Counselling Psychology, 6, 551.