Use a line of negative and positive measurements to show the location of -2.1 whether negative or positive? Please any sample of this?

Sure! Here is a sample line of negative and positive measurements showing the location of -2.1:

-3 | -2.5 | -2.1 | -1.5 | -1

In this line, -2.1 is located between -2.5 and -1.5, indicating that it is closer to -2 than to -1.