I'd like to resize the field for the feedback answer from 80 to 200.
What sources must be modified?
You do not say so but, from your screenshot I guess you are using the so-called "short answer" question type in Moodle.
- Please note it's called short answer, not longish answer.
- You say you want to "resize the field for the feedback answer", but in fact you do not want to resize the feedback field but the student's answer input field.
- Even though that answer field is limited to displaying 80 characters at a time, its contents are not limited.
- Finally, from a pedagogical point of view I fail to understand what you are trying to achieve. I do not understand your instructions ("Direction"). Maybe you should look for another type of question or activity in Moodle to better achieve your aims.