how to measure line segment?

Hello. According to the question, AB=BC=10, and points are all found on one line, so A, B, C are on one line. You can draw a graph of three points. (in the graph, the order of Points is A, B,C)

A__________B__________C

Because the coordinate of A is 2, and the coordinate of B is greater than A, so the coordinate of B is 12, not -8. (Point B must be on the right of Point A).

Moreover, the coordinate of C is 22, because BC=10. Even though the question don't ask, I think it is correct. C may be also share the same point as A, but usually, C is different than A. So C is 22