Redoing this pull request without the other unwanted commits.
I've added a new solution box to the question whenever you divide by an expression so you have to include the domain condition as part of your answer.
It's formatted using a table isn't isn't ideal especially as tabbing from one box to another goes in an unintuitive order, but it seemed better than creating a lot more divs and trying to line them up.
Addresses issue #43362
Include a solution box for the domain of the expression
Remove redundant variable
Split final hint