They are the same distance from 0 on a number line.
http://img.sparknotes.com/figures/5/50ca5e784bb7e4242910d5b8a571d103/number_line.gif
Explain why 2.15 and -2.15 are opposites.
3 answers
explain why 2.15 and -2.15 are opposites
Graph each number and its opposite on a number