I posted a question about these a few days ago and am still having trouble understanding this. If someone could show me how to do this problem with some explanation hopefully I can understand it better.

Find a value of alpha > 0 such that for all x, 0 < abs value (x- Xo) < alpha -> a<x<b.

a= -7/2 b= -1/2 Xo= -3

Our teacher barely does an examples in class, and I don't even understand what this problem is looking for. Thanks for help!