Answer:
1. a = b
2. b = c
3. a = c
Explanation:
This is a case of transitive property.
You'll see this soon enough if you haven't yet:
If a = b and b = c, then a = c.
Your problem is the same, but instead of using a, b, and c, your problem uses number lines.
I hope this is helpful!
If you have any questions then feel free to leave a comment!