Here's the math problem that I need help with. I am supposed to identify the properties with each step.

(9-b) - 4 = [9 + (-b)] -4
= [9 + (-b)] + (-4)
= 9 + [(-b) + (-4)]
= 9 +[-4 + (-b)
= [9 + (-4)] + (-b)
= 5 + (-b)
= 5 - b

a.
b.
c.
d.
e.
f. substitution
g.

I'm not that great with properties, so if you could explain your answer, that would be great!