By double clicking or by pressing enter and continuing on a new line in the field that you're editing, a '+' icon appears on the left.
By clicking the '+' icon, an icon with a camera and a summation symbol appear. You can add an image to the field by clicking the camera icon and uploading the image from your computer.
When you click the summation symbol you can add an equation to the exercise with a variety of different possibilities.
When you select a piece of text, a mini editor appears. Using the mini editor, you can edit your text, add a bullet list or enumeration and even add a table or type in an equation. WATCH OUT: when selecting the equation symbol, the text that has been selected disappears.
By clicking the button "add additional answers and feedback", you can specify the info about the exact answer that should be given by your students, in order for the answer to be approved.
In the screen that opens you can add multiple answers and provide specific feedback. Select if a specific answer is correct or incorrect and even give specific feedback depending on which answer is given.
To read more about adding additional answers and specific feedback, check out this article: How to add specific feedback in my exercises?