The type of workbook mentioned by @AlexanderIII looks appropriate for your needs. I would add the “Dummies” algebra series are pretty good too. There are separate books and workbooks in that series. See which ones fit your child’s needs.
While the AOPs books are conversational in tone, the problems skew toward the out of the box types. Many are quite challenging, even at beginning algebra level. If you are looking for that type of challenge, that’s fine. My second kid loves those types of problems, while my first one would just look at them and say “huh?” You can see the excerpts on their website.