What property is used in theses math problems

1: If AB=CD, then CD=AB
2: 5(x-4) = 5x-20
3: 3x-17=8, then 3x=25
4: 22m=440, then m=20
5:(2a+3a)-4a=7a+55, then (5a)-4a=7a+55
6:If GH=2x+17, and 2x+17=JK, then GH=JK
7:2b+(b-7)=17, then (2b+b)-7=17
8:(x+7)/3=13, then x+7=39.
9:m 10:4+x=13, then x+4=13