Well, I've read them. I know what they all state. But I don't get their application.

For reference, this is what my text lists them as:

Addition - If A=B, then A+C = B+C

Subtraction - If A=B, then A-C = B-C

Multiplication - If A=B, then AB=BC

Division - If A=B and C =/= 0, then A/C = B/C

Substitution - If A=B, then B can be used for A in any circumstance.

Symmetry - AB=BA

Transitive - If A=B and B=C, then A=C

Reflexive - AB=AB

...That said, I don't really get their usage.

Here's the segment on them from a recent test I got back, along with my answers. I missed 13, 14, and 16. My answers are bold, and my comments are italicized.

12. If JK = PQ and PQ = ST, then JK = ST.Transitive.

13. If AB + CD = EF + CD, then AB = EF.Addition.I don't get where I went wrong here.

14. AB = AB.Transitive.This is purely me forgetting about Reflexive, and forgetting whether Transitive was the A=A one or the A=B/B=C:A=C one.

15. If AB = CD, then CD = AB.Symmetric.

16. If AB - CD = EF - CD, then AB = EF.Subtraction.Same song as 13. Not sure where I went wrong.

I got the rest of the test right, except for one problem I just made an easy-to-fix stupid mistake on. So these alone are causing me problems. Help, please?