I think the answers are:
Statement Reason
12=13x+5 Given
7=13x Subtraction Property of Equality
21 = x Multiplication Property of Equality
x = 21 Symmetric Property of Equality
By the way, I'm doing the same exam for Geometry as well. There's a lot of proof questions on there which I'm not good at doing for the reasoning part. If you finish the exam before I do, maybe you can message me what the answers are for some of the questions on there so I know if my answers for the questions are incorrect or not.
Besides that, hope the answer above is correct for you.
~ ShadowXReaper069