Prove that the following relation is an equivalence relation and determine how many equivalence classes R partitions the set $Z^{+}$ into.
R = {$(a,b) | a∈Z^{+} ∧ b∈Z^{+} ∧ 10 | (a^{2}- b^{2})$}
Any help would be great. I would love an explanation, in layman's terms, of what I'm looking at. Thanks!